Process for converting a hydrocarbon to an oxygenate or a nitrile

ABSTRACT

This invention relates to a process for converting a hydrocarbon reactant to a product comprising an oxygenate or a nitrile, the process comprising: (A) flowing a reactant composition comprising the hydrocarbon reactant, and oxygen or a source of oxygen, and optionally ammonia, through a microchannel reactor in contact with a catalyst to convert the hydrocarbon reactant to the product, the hydrocarbon reactant undergoing an exothermic reaction in the microchannel reactor; (B) transferring heat from the microchannel reactor to a heat exchanger during step (A); and (C) quenching the product from step (A).

This application is a continuation application of U.S. application Ser.No. 10/429,286, filed May 2, 2003. This prior application isincorporated herein by reference.

TECHNICAL FIELD

This invention relates to a process for converting a hydrocarbonreactant to an oxygenate or a nitrite using microchannel processtechnology.

BACKGROUND OF THE INVENTION

Oxidation reactions typically involve reacting a hydrocarbon with oxygenin the presence of a catalyst to form an oxygenate. Examples include theconversion of methane to methanol or formaldehyde; ethane or ethylene toethyl alcohol, ethylene oxide, acetic acid or vinyl acetate; orpropylene to acrylic acid or acrolein. Ammoxidation reactions typicallyinvolve reacting a hydrocarbon with oxygen and ammonia in the presenceof a catalyst to form a nitrile. Examples include the conversion ofpropane or propylene to acrylonitrile, and isobutane or isobutylene tomethacrylonitrile.

A problem with each of these reactions is that they are exothermic andare typically conducted in fixed bed reactors where hot spots tend toform. The formation of these hot spots lowers selectivity towards thedesired main product in favor of parallel reactions that form undesiredproducts such as carbon oxides (i.e., CO, CO₂). The present inventionprovides a solution to this problem by conducting the reaction in amicrochannel reactor wherein the tendency to form hot spots is reducedand selectivity to the desired product is enhanced. Enhanced selectivitywith the inventive process is believed to be due at least in part to thefact that the microchannel reactor provides enhanced heat transfercharacteristics and more precise control of residence times. Also, theinternal dimensions of the microchannel reactor can be set at a levelequal to or below the quench diameter for unwanted reactions.

With the inventive process it is possible to obtain relatively high heatand mass transfer rates and shorter contact times as compared to priorart processes wherein microchannel reactors are not used. This providesfor more precise temperature control as compared to such prior art.This, in turn, leads to reduced peak temperatures and a reduction in theformation of undesired by-products. With this process, it is possible toobtain relatively high levels of conversion of the hydrocarbon reactantand high levels of selectivity to the desired product as compared tosuch prior art.

SUMMARY OF THE INVENTION

This invention relates to a process for converting a hydrocarbonreactant to a product comprising an oxygenate or a nitrile, the processcomprising:

(A) flowing a reactant composition comprising the hydrocarbon reactant,and oxygen or a source of oxygen, and optionally ammonia, through amicrochannel reactor in contact with a catalyst to convert thehydrocarbon reactant to the product, the hydrocarbon reactant undergoingan exothermic reaction in the microchannel reactor;

(B) transferring heat from the microchannel reactor to a heat exchangerduring step (A); and

(C) quenching the product from step (A).

BRIEF DESCRIPTION OF THE DRAWINGS

In the annexed drawings, like parts and features have like designations.

FIG. 1 is a schematic flow sheet illustrating the inventive process in aparticular form wherein a fluid hydrocarbon reactant is converted to anoxygenate or nitrile in a microchannel reactor.

FIG. 2 is a schematic flow sheet illustrating an alternate embodiment ofthe inventive process.

FIG. 3A is a schematic flow sheet illustrating another alternateembodiment of the inventive process.

FIG. 3B is a schematic flow sheet illustrating the operation of aparticular form of a microchannel reactor used with the inventiveprocess.

FIG. 4 is a schematic illustration of a cross flow reactor embodying aparticular form of a microchannel reactor for conducting the inventiveprocess.

FIG. 5 is a schematic illustration of a cross-sectional view of aprocess microchannel used with the inventive process, the processmicrochannel containing a catalyst having a flow-by configuration.

FIG. 6 is a cross-sectional view of an alternate embodiment of theprocess microchannel used with the inventive process, the processmicrochannel containing a catalyst having a flow-through configuration.

DETAILED DESCRIPTION OF THE INVENTION

The term “microchannel” refers to a channel having at least one internaldimension of height or width (wall-to-wall, not counting catalyst) of upto about 10 millimeters (mm), and in one embodiment up to about 5 mm,and in one embodiment up to about 2 mm, and in one embodiment up toabout 1 mm. In one embodiment, the height or width is in the range ofabout 0.05 to about 10 mm, and in one embodiment about 0.05 to about 5mm, and in one embodiment about 0.05 to about 2 mm, and in oneembodiment about 0.05 to about 1.5 mm, and in one embodiment about 0.05to about 1 mm, and in one embodiment about 0.05 to about 0.75 mm, and inone embodiment about 0.05 to about 0.5 mm. Both height and width areperpendicular to the direction of flow through the microchannel.

The term “adjacent” when referring to the position of one channelrelative to the position of another channel means directly adjacent suchthat a wall separates the two channels. This wall may vary in thickness.However, “adjacent” channels are not separated by an intervening channelthat would interfere with heat transfer between the channels.

The term “fluid” refers to a gas, a liquid, or a gas or a liquidcontaining dispersed solids, or a mixture thereof. The fluid may be inthe form of a gas containing dispersed liquid droplets.

The term “contact time” refers to the volume of the reaction zone withinthe microchannel reactor divided by the volumetric feed flow rate of thereactant composition at a temperature of 0° C. and a pressure of oneatmosphere.

The term “residence time” refers to the internal volume of a space(e.g., the reaction zone within a microchannel reactor) occupied by afluid flowing through the space divided by the average volumetricflowrate for the fluid flowing through the space at the temperature andpressure being used.

The term “reaction zone” refers to the space within the microchannelreactor wherein the reactants contact the catalyst.

The term “conversion of hydrocarbon reactant” refers to the hydrocarbonreactant mole change between the reactant composition and the productdivided by the moles of the hydrocarbon reactant in the reactantcomposition.

The term “selectivity to desired product” refers to the moles of thedesired oxygenate or nitrile produced divided by the moles of thedesired oxygenate or nitrile produced plus moles of other products(e.g., CO, CO₂) produced multiplied by their respective stoichiometricfactors. For example, for the oxidation of ethylene to ethylene oxidewith carbon dioxide as an unwanted side product, the production of onemole of ethylene oxide and one mole of carbon dioxide would correspondto a selectivity of 100×(1/(1+0.5))=67%.

The term “hydrocarbon” denotes a compound having a hydrocarbon orpredominantly hydrocarbon character. These hydrocarbon compounds includethe following:

(1) Purely hydrocarbon compounds; that is, aliphatic compounds, (e.g.,alkane or alkylene), alicyclic compounds (e.g., cycloalkane,cycloalkylene), aromatic compounds, aliphatic- and alicyclic-substitutedaromatic compounds, aromatic-substituted aliphatic compounds andaromatic-substituted alicyclic compounds, and the like. Examples includemethane, ethane, ethylene, propane, propylene, ethyl cyclohexane,toluene, the xylenes, ethyl benzene, styrene, etc.

(2) Substituted hydrocarbon compounds; that is, hydrocarbon compoundcontaining non-hydrocarbon substituents which do not alter thepredominantly hydrocarbon character of the compound. Examples of thenon-hydrocarbon substituents include hydroxy, acyl, nitro, etc.

(3) Hetero substituted hydrocarbon compounds; that is, hydrocarboncompounds which, while predominantly hydrocarbon in character, containatoms other than carbon in a chain or ring otherwise composed of carbonatoms. Suitable hetero atoms include, for example, nitrogen, oxygen andsulfur.

The term “oxygenate” refers to a hydrocarbon product containing at leastone oxygen atom; CO and CO₂ are excluded. Examples include alcohols(e.g., methanol, ethyl alcohol), epoxides (e.g., ethylene oxide),aldehydes (e.g., formaldehyde, acrolein), carboxylic acids (e.g., aceticacid, acrylic acid), carboxylic acid anhydrides (e.g., maleicanhydride), esters (e.g., vinyl acetate), and the like.

The term “quench” refers to a process by which a chemical reaction isterminated or substantially terminated using a rapid reduction intemperature of the reactants, a rapid introduction of a reactant ornon-reactant fluid into the reactant mixture, or flowing the reactantsthrough a restricted opening or passageway having a dimension at orbelow the quench diameter.

The term “quench diameter” refers to the internal dimension (e.g.,height, width, diameter) of an opening or passageway for the reactantsto flow through below which the reaction terminates or substantiallyterminates.

The inventive process will be described initially with reference toFIG. 1. Referring to FIG. 1, microchannel reactor 100 is comprised of aheader 102, a plurality of process microchannels 104 which contain acatalyst 106 and operate in parallel, and a footer 108. The header 102provides a passageway for fluid to flow into the process microchannels104 with an even or substantially even distribution of flow to theprocess microchannels. The footer 108 provides a passageway for fluid toflow from the process microchannels 104 in a rapid manner with arelatively high rate of flow.

There is practically no upper limit to the number of processmicrochannels 104 that may be used in microchannel reactor 100. Forexample, the microchannel reactor 100 may contain one, two, three, four,five, six, eight, ten, twenty, fifty, one hundred, hundreds, onethousand, thousands, ten thousand, tens of thousands, one hundredthousand, hundreds of thousands, millions, etc., of the processmicrochannels 104. These process microchannels may be arranged inparallel, for example, in arrays of planar microchannels. Themicrochannel reactor may be of the microcomponent sheet architecturevariety such as disclosed in U.S. Pat. No. 6,200,536B1, which isincorporated herein by reference. Each of the process microchannels 104may have at least one internal dimension of height or width of up toabout 10 mm, and in one embodiment from about 0.05 to about 10 mm, andin one embodiment about 0.05 to about 5 mm, and in one embodiment about0.05 to about 2 mm, and in one embodiment about 0.05 to about 1.5 mm,and in one embodiment about 0.05 to about 1 mm, and in one embodimentabout 0.05 to about 0.5 mm. The other internal dimension of height orwidth may be of any value, for example, it may range from about 0.1 cmto about 100 cm, and in one embodiment from about 0.1 to about 75 cm,and in one embodiment from about 0.1 to about 50 cm, and in oneembodiment about 0.2 cm to about 25 cm. The length of each of theprocess microchannels 104 may be of any value, for example, it may rangefrom about 1 cm to about 500 cm, and in one embodiment 1 cm to about 250cm, and in one embodiment 1 cm to about 100 cm, and in one embodiment 1cm to about 50 cm, and in one embodiment about 2 to about 25 cm.

In one embodiment, the process microchannels 104 contain a bulk flowpath. The term “bulk flow path” refers to an open path (contiguous bulkflow region) within the process microchannels. A contiguous bulk flowregion allows rapid fluid flow through the microchannels without largepressure drops. In one embodiment, the flow of fluid in the bulk flowregion is laminar. Bulk flow regions within each process microchannelmay have a cross-sectional area of about 0.05 to about 10,000 mm², andin one embodiment about 0.05 to about 5000 mm², and in one embodimentabout 0.1 to about 2500 mm², and in one embodiment about 0.2 to about1000 mm², and in one embodiment about 0.3 to about 500 mm², and in oneembodiment about 0.4 to about 250 mm², and in one embodiment about 0.5to about 125 mm². The bulk flow regions may comprise from about 5% toabout 95%, and in one embodiment about 30% to about 80% of thecross-section of the process microchannels 104.

The header 102, footer 108 and the process microchannels 104 may be madeof any material that provides sufficient strength, dimensional stabilityand heat transfer characteristics to permit operation of the inventiveprocess. These materials include steel (e.g., stainless steel, carbonsteel, and the like); monel; inconel; aluminum, titanium; nickel,platinum; rhodium; copper; chromium; brass; alloys of any of theforegoing metals; polymers (e.g., thermoset resins); ceramics; glass;composites comprising one or more polymers (e.g., thermoset resins) andfiberglass; quartz; silicon; or a combination of two or more thereof.

The reactant composition that flows into the microchannel reactor 100comprises a hydrocarbon reactant, oxygen or a source of oxygen, andoptionally ammonia. The hydrocarbon reactant flows through line 120 intoheader 102. The oxygen or oxygen source flows through line 122 intoheader 102. When used, the ammonia flows through line 124 into header102. The reactant composition is mixed in header 102 and flows throughprocess microchannels 104 in contact with catalyst 106. Alternatively,the reactants may be mixed in the process microchannels 104 using mixersdisposed within the process microchannels. In one embodiment, amicrochannel mixer feeding reactants into the header 102 may be useful.With such a microchannel mixer, adjacent microchannels in the mixercontain the different reactants which mix rapidly on leaving theirrespective microchannels in the header region. Optionally, one or moreof the reactants (e.g., the oxygen or oxygen source) may be added to themain reactant flow at different points along the length of microchannelto control the heat release along the length of the microchannel. Withinthe process microchannels 104 the reactant composition undergoes anexothermic reaction resulting in the formation of the product. Theproduct flows through the process microchannels 104 into footer 108. Theproduct flows from footer 108 through line 130 to valve 132, throughvalve 132 to line 134, and from line 134 to quenching apparatus 136wherein the product is quenched. The quenched product exits quenchingapparatus 136 through line 138. In one embodiment, the quenched productexiting quenching apparatus 136 flows through a second quenchingapparatus or stage without flowing through an intermediate valve.

Optionally, the product and unreacted parts from the reactantcomposition may be further processed in a second microchannel reactorthat is similar in design and operation to microchannel reactor 100, orthey may be recycled from valve 132 to line 144, through line 144 toline 146, through line 146 to line 148, through line 148 to line 150,and through line 150 into the microchannel reactor 100. In oneembodiment, the desired product may be separated from the unreactedparts of the reactant composition using known techniques, and theunreacted parts may be further processed in a second microchannelreactor similar in design and operation to the microchannel reactor 100or they may be recycled back to the microchannel reactor 100 asdescribed above. However, an advantage of the inventive process is thatit is possible to obtain a relatively high level of conversion of thehydrocarbon reactant in a single cycle or a single pass through themicrochannel reactor, that is, without the foregoing recycle step orfurther processing in a second reactor.

During the inventive process, the reaction within the processmicrochannels 104 is exothermic and the microchannel reactor 100 iscooled using a heat exchanger in thermal contact with the processmicrochannels 104. The heat exchanger may be in the form of heatexchange channels (not shown in the drawings) adjacent to the processmicrochannels 104. The heat exchange channels may be microchannels. Aheat exchange fluid flows from heat exchange header 110 through the heatexchange channels to heat exchange footer 112. The heat exchangechannels may be aligned to provide a flow in a cross-current directionrelative to the process microchannels 104 as indicated by arrows 1 14and 1 16. The process microchannels 104 transfer heat to the heatexchange channels. The heat exchange fluid may be recirculated usingknown techniques. Alternatively, the heat exchange channels may beoriented to provide for flow of the heat exchange fluid in a cocurrentor counter current direction relative to the direction of the flow offluid through the process microchannels 104.

Each of the heat exchange channels may have at least one internaldimension of height or width of up to about 10 mm, and in one embodimentabout 0.05 to about 10 mm, and in one embodiment about 0.05 to about 5mm, and in one embodiment from about 0.05 to about 2 mm, and in oneembodiment from about 0.5 to about 1 mm. The other internal dimensionmay range from about 1 mm to about 1 m, and in one embodiment about 1 mmto about 0.5 m, and in one embodiment about 2 mm to about 10 cm. Thelength of the heat exchange channels may range from about 1 mm to about1 m, and in one embodiment about 1 cm to about 0.5 m. The separationbetween each process microchannel 104 and the next adjacent heatexchange channel may range from about 0.05 mm to about 5 mm, and in oneembodiment about 0.2 mm to about 2 mm.

The heat exchange channels may be made of any material that providessufficient strength, dimensional stability and heat transfercharacteristics to permit the operation of the inventive process. Thesematerials include: steel (e.g., stainless steel, carbon steel, and thelike); monel; inconel; aluminum; titanium; nickel; platinum; rhodium;copper; chromium; brass; alloys of any of the foregoing metals; polymers(e.g., thermoset resins); ceramics; glass; composites comprising one ormore polymers (e.g., thermoset resins) and fiberglass; quartz; silicon;or a combination of two or more thereof.

The heat exchange fluid may be any fluid. These include air, steam,liquid water, gaseous nitrogen, liquid nitrogen, other gases includinginert gases, carbon monoxide, molten salt, oils such as mineral oil, andheat exchange fluids such as Dowtherm A and Therminol which areavailable from Dow-Union Carbide.

The heat exchange fluid may comprise one or more of the reactantstreams. This can provide process pre-heat and increase overall thermalefficiency of the process.

In one embodiment, the heat exchange channels comprise process channelswherein an endothermic reaction is conducted. These heat exchangeprocess channels may be microchannels. Examples of endothermic reactionsthat may be conducted in the heat exchange channels include steamreforming and dehydrogenation reactions. A typical heat flux forconvective cooling in a microchannel reactor is on the order of about 1to about 10 W/cm². The incorporation of a simultaneous endothermicreaction to provide an improved heat sink may enable a typical heat fluxof roughly an order of magnitude above the convective cooling heat flux.

In one embodiment, the heat exchange fluid undergoes a phase change asit flows through the heat exchange channels. This phase change providesadditional heat removal from the process microchannels beyond thatprovided by convective cooling. For a liquid heat exchange fluid beingvaporized, the additional heat being transferred from the processmicrochannels would result from the latent heat of vaporization requiredby the heat exchange fluid. An example of such a phase change would bean oil or water that undergoes boiling.

The added cooling of the process microchannels 104 provided by step (B)of the inventive process is essential to controlling selectivity towardsthe main or desired product due to the fact that such added coolingreduces or eliminates the formation of undesired by-products fromundesired parallel reactions with higher activation energies. As aresult of this added cooling, in one embodiment, the temperature of thereactant composition at the entrance to the process microchannels 104may be within (plus or minus) about 200° C., and in one embodimentwithin about 150° C., and in one embodiment within about 100° C., and inone embodiment within about 50° C., and in one embodiment within about25° C., and in one embodiment within about 10° C., of the temperature ofthe product (or mixture of product and unreacted reactants) at the exitof the process microchannels. In one embodiment, the reaction within theprocess microchannels 104 is conducted under isothermal or nearisothermal conditions as a result of such added cooling.

The microchannel reactor 100 may be made using known techniques. Theseinclude laminating interleaved shims, where shims designed for theprocess microchannels 104 are interleaved with shims designed for theheat exchange channels.

The quenching apparatus 136 may comprise a heat exchange apparatuscapable of reducing the temperature of the product flowing from themicrochannel reactor by up to about 950° C. within a period of up toabout 500 milliseconds (ms). The temperature may be reduced by up toabout 50° C., and in one embodiment up to about 100° C., and in oneembodiment up to about 250° C., and in one embodiment up to about 500°C., and in one embodiment up to about 750° C., within a time period ofup to about 500 ms, and in one embodiment up to about 400 ms, and in oneembodiment up to about 300 ms, and in one embodiment up to about 200 ms,and in one embodiment up to about 100 ms, and In one embodiment up toabout 50 ms, and in one embodiment up to about 35 ms, and in oneembodiment up to about 20 ms, and in one embodiment up to about 15 ms,and in one embodiment up to about 10 ms, and in one embodiment within atime period of up to about 5 ms. In one embodiment, the temperature isreduced by up to about 500° C. within a time period of about 5 to about100 ms, and in one embodiment about 10 to about 50 ms. The quenchingapparatus may be integral with the microchannel reactor, or it may beseparate from the microchannel reactor. The quenching apparatus maycomprise a microchannel heat exchanger. The quenching apparatus maycomprise a heat exchanger that is adjacent to or interleaved with theproduct stream exiting the microchannel reactor. The quenching apparatusmay comprise a mixer capable of rapidly mixing the product with asecondary cooling fluid. The secondary cooling fluid may be a lowtemperature steam or a condensable hydrocarbon injected as a liquid.

Alternatively, the quenching apparatus may comprise a narrow gap orpassageway for the reactants to flow through, the gap or passagewayhaving a dimension equal to or below the quench diameter for thereaction. In this embodiment, the reaction terminates as the reactantsflow through the gap or passageway as a result of wall collisions. Thegap or passageway may have a height or width of up to about 5 mm, and inone embodiment up to about 3 mm, and in one embodiment up to about 1 mm,and in one embodiment up to about 0.5 mm, and in one embodiment up toabout 0.1 mm, and in one embodiment up to about 0.05 mm. This quenchingapparatus may comprise a microchannel or a plurality of parallelmicrochannels. This quenching apparatus may comprise part of the processmicrochannels used with the inventive process downstream of the catalystcontained within the microchannels. The narrow gap or passageway may beused in conjunction with one or more of the other quenching apparatuses(e.g., heat exchangers) discussed above.

The process illustrated in FIG. 2 is the same as illustrated in FIG. 1with the exception that premixing and preheating apparatus 200 has beenadded upstream of the microchannel reactor 100. The premixing andpreheating apparatus may comprise a microchannel mixer that is separatefrom or integral with the microchannel reactor 100. The hydrocarbonreactant enters the premixing and preheating apparatus 200 through line120. The oxygen or oxygen source enters premixing and preheatingapparatus 200 through line 122. When used the ammonia enters premixingand preheating apparatus 200 through line 124. The premixing andpreheating apparatus 200 may be of any conventional design and may beheated using a heat exchange fluid flowing through the apparatus 200 asindicated by arrows 204 and 206. Within the premixing and preheatingapparatus 200, the hydrocarbon reactant, the oxygen or oxygen source andwhen used the ammonia are mixed and heated to the temperature desiredfor entry into the process microchannels 104. The premixed and preheatedreactant composition flows from premixing and preheating apparatus 200through line 202 to header 102. From header 102 the reactant compositionflows through microchannels 104 in contact with catalyst 106, andundergoes an exothermic reaction resulting in the formation of thedesired product. The product flows into the footer 108, and from thefooter 108 through line 130 to valve 132, through valve 132 to line 134,through line 134 to quench apparatus 136 wherein the product isquenched. The quenched product exits quench apparatus 136 through line138. Optionally, the unreacted parts of the reactant composition, andoptionally the product, may be further processed in a secondmicrochannel reactor or recycled from valve 132 to line 144, throughline 144 to line 146, through line 146 to line 148, through line 148 toline 150, and through line 150 into microchannel reactor 100, asdiscussed above.

The premixing and preheating apparatus 200 may comprise any mixingapparatus capable of mixing the hydrocarbon reactant, oxygen or oxygensource, and optionally ammonia, and heating the resulting reactantcomposition to the temperature desired for entry into the microchannelreactor 100. The reactant composition may be heated to a temperature inthe range of about 200° C. to about 800° C., and in one embodiment about300° C. to about 700° C., and in one embodiment about 400° C. to about600° C. Examples of the mixers that may be used include microchannelmixers, gas ejectors, concentric nozzles, jets, and the like. The mixingmay be effected by flowing the reactants into a porous material such asa foam, felt, wad or bed of particulates made of any suitable material,including ceramics, quartz and high temperature metals and alloys suchas Inconel, FeCrAlY, and the like.

The inventive process may be conducted as illustrated in FIGS. 3A and3B. Referring to FIG. 3A, the process is operated using microchannelreactor 300 which includes microchannel reactor core 301, reactantheader 302, oxidant header 304, product footer 306, heat exchange header310, heat exchange footer 312, and quenching apparatus 314. Themicrochannel reactor core 301 includes reactor zone 307, and manifoldand recuperator 308. The reactant composition comprising the hydrocarbonreactant, and optionally ammonia, flows into the microchannel reactor300 through the reactant header 302 as indicated by directional arrow316. The oxygen or source of oxygen flows into the microchannel reactor300 through the oxidant header 304 as indicated by directional arrow318. The hydrocarbon reactant, oxygen or source of oxygen, andoptionally ammonia, flow into and through the manifold and recuperator308 into the reactor zone 307 wherein they contact a catalyst and reactto form the desired product. The product flows from the reactor zone 307through the manifold and recuperator 308 to product footer 306, and fromproduct footer 306 through the quenching apparatus 314 as indicated bydirectional arrows 320 and 322. A heat exchange fluid flows into heatexchange header 310, as indicated by directional arrow 324, and fromheat exchange header 310 through microchannel reactor 301 to heatexchange footer 312, and out of heat exchange footer 312, as indicatedby directional arrow 326. Within the microchannel reactor core 301, theoxygen or source of oxygen is added to the hydrocarbon reactant, andoptionally ammonia, using staged addition. This is illustrated in FIG.3B.

Referring to FIG. 3B, which illustrates repeating unit 330 which is usedin the microchannel reactor 300 illustrated in FIG. 3A, and is housedwithin housing unit 331. The inventive process is conducted usingprocess microchannels 340 and 350, oxidant microchannel 360, orifices370, and heat exchange microchannels 380 and 390. The hydrocarbonreactant, and optionally ammonia, flows through process microchannels340 and 350, as indicated by the directional arrows 341 and 351,respectively. Oxygen or a source of oxygen flows through oxidantmicrochannel 360 into orifices 370, as indicated by directional arrows361. The oxygen or oxygen source mixes with the hydrocarbon reactant,and optionally ammonia, in the process microchannels 340 and 350. Theprocess microchannels 340 and 350 have reaction zones 342 and 352,respectively, wherein the catalyst 106 is present and the reactantscontact the catalyst and undergo reaction, and channel zones 343 and353, respectively, wherein further contact with the catalyst may beeffected or product cooling and/or quenching may be effected. Within theprocess microchannels 340 and 350, the reactants contact the catalystand react to form the desired product. The product exits the processmicrochannels 340 and 350, as indicated by the directional arrows 344and 354, respectively. The product exiting the process microchannels 340and 350 flows to the manifold and recuperator 308, and from the manifoldand recuperator 308 through the product footer 306 to the quenchingapparatus 314, as indicated above. The quenched product exits thequenching apparatus 314, as indicated by directional arrow 322. Heatexchange fluid flows from header 310 through heat exchange channels 380and 390, as indicated by directional arrows 381, and 391 and 392,respectively, to heat exchange footer 312. The repeating unit 330illustrated in FIG. 3B may occur once within the microchannel reactor300 or it may be repeated any number of times, for example, two, three,four, five, ten, twenty, fifty, one hundred, hundreds, one thousand,thousands, ten thousand, tens of thousands, one hundred thousand,hundreds of thousands or millions of times. The staged oxygen additionprovided for in this process provides the advantage of lowering localoxygen pressure and favoring desired lower-order partial oxidationreactions over higher-order competing and undesired combustionreactions.

Each of the process microchannels 340 and 350 and the oxidantmicrochannel 360 may have at least one internal dimension of height orwidth of up to about 10 mm, and in one embodiment from about 0.05 toabout 10 mm, and in one embodiment about 0.05 to about 5 mm, and in oneembodiment about 0.05 to about 2 mm, and in one embodiment about 0.05 toabout 1.5 mm, and in one embodiment about 0.05 to about 1 mm, and in oneembodiment about 0.05 to about 0.5 mm. The other internal dimension ofheight or width may be of any value, for example, it may range fromabout 0.1 cm to about 100 cm, and in one embodiment from about 0.1 toabout 75 cm, and in one embodiment from about 0.1 to about 50 cm, and inone embodiment about 0.2 cm to about 25 cm. The length of each of theprocess microchannels 340 and 350, and the oxidant microchannel 360, maybe of any value, for example, the lengths may range from about 1 cm toabout 500 cm, and in one embodiment 1 cm to about 250 cm, and in oneembodiment 1 cm to about 100 cm, and in one embodiment 1 cm to about 50cm, and in one embodiment about 2 to about 25 cm.

Each of the heat exchange channels 380 and 390 may have at least oneinternal dimension of height or width of up to about 10 mm, and in oneembodiment about 0.05 to about 10 mm, and in one embodiment about 0.05to about 5 mm, and in one embodiment from about 0.05 to about 2 mm, andin one embodiment from about 0.5 to about 1 mm. The other internaldimension may range from about 1 mm to about 1 m, and in one embodimentabout 1 mm to about 0.5 m, and in one embodiment about 2 mm to about 10cm. The length of the heat exchange channels may range from about 1 mmto about 1 m, and in one embodiment about 1 cm to about 0.5 m. Theseheat exchange channels may be microchannels. The separation between eachprocess microchannel 340 or 350 and the next adjacent heat exchangechannel 380 or 390 may range from about 0.05 mm to about 5 mm, and inone embodiment about 0.2 mm to about 2 mm.

The housing 301, process microchannels 340 and 350, oxidant microchannel360, and heat exchange channels 380 and 390 may be made of any materialthat provides sufficient strength, dimensional stability and heattransfer characteristics to permit operation of the inventive process.These materials include steel (e.g., stainless steel, carbon steel, andthe like); monel; inconel; aluminum, titanium; nickel, platinum;rhodium; copper; chromium; brass; alloys of any of the foregoing metals;polymers (e.g., thermoset resins); ceramics; glass; compositescomprising one or more polymers (e.g., thermoset resins) and fiberglass;quartz; silicon; or a combination of two or more thereof.

Alternatively, the staged addition of the oxygen or source of oxygen tothe microchannel reactor may be effected using separate devices, throughthe use of small orifices or jets within one device, or from amicroporous membrane or alternate sparging sheet. The staged addition ofoxygen to partial oxidation reactions, and specifically oxidativedehydrogenation reactions, is disclosed in Tonkovich, Zilka, Jimenz,Roberts, and Cox, 1996, “Experimental Investigations of InorganicMembrane Reactors: a Distributed Feed Approach for Partial OxidationReactions,” Chemical Engineering Science, 51(5), 789-806), which isincorporated herein by reference.

The inventive process may be conducted in microchannel reactor 100Awhich is illustrated in FIG. 4. Referring to FIG. 4, microchannelreactor 100A contains an array of process microchannels 104 which extendparallel to each other and are arranged in rows 400. The rows 400 arepositioned in separate planes one above another. The microchannelreactor 100A also contains an array of heat exchange microchannels 420extending parallel to each other and arranged in rows 422. The rows 422of heat exchange microchannels 420 are positioned in separate planes oneabove another. The heat exchange microchannels 420 extend transverselyof and in thermal contact with the process microchannels 104. The rows422 of heat exchange microchannels 420, and the rows 400 of processmicrochannels 104 are positioned in separate alternating planes oneabove another.

The microchannel reactor 100A contains nine rows 400 of process channels104, with six process microchannels 104 in each row 400 for a total of54 process microchannels 104. It is to be understood, however, that themicrochannel reactor 100A may contain any number of processmicrochannels 104, for example, hundreds, thousands, tens of thousands,hundreds of thousands, or millions of process microchannels 104.Similarly, the microchannel reactor 100A contains 10 rows 422 of heatexchange microchannels 420. Each row 422 contains 11 heat exchangemicrochannels 420 for a total of 110 heat exchange microchannels 420. Itis to be understood, however, that although the illustrated microchannelreactor contains a total of 110 heat exchange microchannels 420,additional heat exchange microchannels 420, for example, thousands, tensof thousands, hundreds of thousands, or millions of heat exchangemicrochannels 420 may be employed with the microchannel reactor 100A.

The process microchannels 104 in microchannel reactor 100A have crosssections in the form of squares or rectangles. The smallest internaldimension for each process microchannel 104, whether it be height orwidth, may be up to about 10 mm, and in one embodiment from about 0.05to about 10 mm, and in one embodiment from about 0.05 to about 5 mm, andin one embodiment about 0.05 to about 2 mm, and in one embodiment about0.05 to about 1.5 mm. The other internal dimension of height or widthmay be in the range of about 0.1 to about 100 cm, and in one embodimentabout 0.2 to about 25 cm. The length of each process microchannel 104may be from about 1 to about 500 cm, and in one embodiment about 1 toabout 250 cm, and in one embodiment about 1 to about 100 cm, and in oneembodiment about 1 to about 50 cm, and in one embodiment about 2 toabout 25 cm.

Each heat exchange microchannel 420 may have a cross section in the formof a square, rectangle, triangle, diamond, circle or elipse and has awidth or height of about 0.025 to about 10 mm, and in one embodimentabout 0.05 to about 5 mm, and in one embodiment about 0.1 to about 2 mm.The length of each heat exchange microchannel 420 may range from about 1mm to about 1 meter, and in one embodiment about 1 cm to about 0.5meter.

The separation between each row 422 of heat exchange microchannels 420and the next adjacent row 400 of process microchannels 104 may rangefrom about 0.05 to about 10 mm, and in one embodiment about 0.1 to about5 mm, and in one embodiment about 0.1 to about 2 mm.

During the operation of the inventive process, the reactant compositionand product flow through the process microchannels 104 in the directionindicated by arrow 430. The catalyst 106 is contained within the processmicrochannels 104. A heat exchange fluid flows through the heat exchangemicrochannels 420 in the direction indicated by arrow 432.

The microchannel reactor 100A may be constructed of any material thatprovides sufficient strength, dimensional stability and heat transfercharacteristics for carrying out the inventive process. Examples ofsuitable materials include steel (e.g., stainless steel, carbon steel,and the like), aluminum, titanium, nickel, and alloys of any of theforegoing metals, plastics (e.g., epoxy resins, UV cured resins,thermosetting resins, and the like), monel, inconel, ceramics, glass,composites, quartz, silicon, or a combination of two or more thereof.The microchannel reactor 100A may be fabricated using known techniquesincluding wire electrodischarge machining,conventional machining, lasercutting, photochemical machining, electrochemical machining, molding,water jet, stamping, etching (for example, chemical, photochemical orplasma etching) and combinations thereof. The microchannel reactor 100Amay be constructed by forming layers or sheets with features removedthat allow flow passages. A stack of sheets may be assembled viadiffusion bonding, laser welding, diffusion brazing, and similar methodsto form an integrated device. The microchannel reactor 100A hasappropriate headers, footers, valves, conduit lines, etc. to controlinput of the reactants, output of the product, and flow of the heatexchange fluid. These are not shown in FIG. 4, but can be readilyprovided by those skilled in the art.

The reactant composition may be in the form of a fluid. This fluid maybe a liquid or a gas, and in one embodiment it is in the form of a gas.This fluid may be in the form of a gas containing dispersed liquiddroplets. The reactant composition comprises at least one hydrocarbonreactant.

The purity of the reactant composition is not critical, though it isdesirable to avoid the presence of compounds which may poison thecatalyst. As a result, the reactant composition may further compriseimpurities such as air, carbon dioxide, and the like.

The reactant composition may include a diluent material. Examples ofsuch diluents include nitrogen, helium, carbon dioxide, liquid water,steam, and the like. The volume ratio of diluent to hydrocarbon reactantin the reactant composition may range from zero to about 80% by volume,and in one embodiment from zero to about 50% by volume. However, anadvantage of at least one embodiment of the invention is that it ispossible to conduct the inventive process without the use of suchdiluents, thus a more efficient and compact process may be provided.

The hydrocarbon reactant may comprise any hydrocarbon compound that iscapable of undergoing an oxidation or ammoxidation reaction, and is afluid (and in one embodiment a vapor) at the temperature and pressureused within the process microchannels. Examples include saturatedaliphatic compounds (e.g., alkanes), unsaturated aliphatic compounds(e.g., monoenes, polyenes, and the like), aldehydes, alkyl substitutedaromatic compounds, alkylene substituted aromatic compounds, and thelike.

The saturated aliphatic compounds include alkanes containing 1 to about20 carbon atoms per molecule, and in one embodiment 1 to about 18 carbonatoms, and in one embodiment 1 to about 16 carbon atoms, and in oneembodiment 1 to about 14 carbon atoms, and in one embodiment 1 to about12 carbon atoms, and in one embodiment 1 to about 10 carbon atoms, andin one embodiment 1 to about 8 carbon atoms, and in one embodiment 1 toabout 6 carbon atoms, and in one embodiment 1 to about 4 carbon atoms.These include methane, ethane, propane, isopropane, butane, isobutane,the pentanes, the hexanes, the heptanes, the octanes, the nonanes, thedecanes, and the like.

The unsaturated aliphatic compounds include alkenes or alkylenescontaining 2 to about 20 carbon atoms, and in one embodiment 2 to about18 carbon atoms, and in one embodiment 2 to about 16 carbon atoms, andin one embodiment 2 to about 14 carbon atoms, and in one embodiment 2 toabout 12 carbon atoms, and in one embodiment 2 to about 10 carbon atoms,and in one embodiment 2 to about 8 carbon atoms, and in one embodiment 2to about 6 carbon atoms per molecule, and in one embodiment 2 to about 4carbon atoms. These include ethylene; propylene; 1-butene; 2-butene;isobutylene; 1-pentene; 2-pentene; 3-methyl-1-butene; 2-methyl-2-butene;1-hexene; 2,3-dimethyl-2-butene; 1-heptene; 1-octene; 1-nonene;1-decene; and the like.

The unsaturated aliphatic compounds may comprise polyenes. These includedienes, trienes, and the like. These compounds may contain 3 to about 20carbon atoms per molecule, and in one embodiment 3 to about 18 carbonatoms, and in one embodiment 3 to about 16 carbon atoms, and in oneembodiment 3 to about 14 carbon atoms, and in one embodiment 3 to about12 carbon atoms, and in one embodiment 3 to about 10 carbon atoms, andin one embodiment about 4 to about 8 carbon atoms, and in one embodimentabout 4 to about 6 carbon atoms. Examples include 1,2-propadiene (alsoknown as allene); 1,3-butadiene; 2-methyl-1,3-butadiene (also known asisoprene); 1,3-pentadiene; 1,4-pentadiene; 1,5-hexadiene; 2,4-hexadiene;2,3-dimethyl-1,3-butadiene; and the like.

The aldehydes may be saturated or unsaturated. They may be aliphatic oraromatic. The aldehydes may contain 1 to about 20 carbon atoms permolecule, and in one embodiment 1 to about 18 carbon atoms, and in oneembodiment 1 to about 16 carbon atoms, and in one embodiment 1 to about14 carbon atoms, and in one embodiment 1 to about 12 carbon atoms, andin one embodiment 1 to about 10 carbon atoms, and in one embodiment 1 toabout 8 carbon atoms, and in one embodiment about 2 to about 8 carbonatoms, and in one embodiment about 3 to about 6 carbon atoms. Examplesinclude formaldehyde; acetaldehyde; propionaldehyde; n-butyraldehyde;n-valeraldehyde; caproaldehyde; acrolein; tran-2-cis-6-nonadienal;n-heptylaldehyde; trans-2-hexenal; hexadeconal; benzaldehyde;phenylacetaldehyde; o-tolualdehyde; m-tolualdehyde; p-tolualdehyde;salicylaldehyde; p-hydroxybenzaldehyde; and the like.

The alkyl or alkylene substituted aromatic compounds may contain one ormore alkyl or alkylene substituents. These compounds may be monocyclic(e.g., phenyl) or a polycyclic (e.g., naphthyl). These compounds includealkyl substituted aromatic compounds containing one or more alkyl groupscontaining 1 to about 20 carbon atoms, and in one embodiment 1 to about18 carbon atoms, and in one embodiment 1 to about 16 carbon atoms, andin one embodiment 1 to about 14 carbon atoms, and in one embodiment 1 toabout 12 carbon atoms, and in one embodiment 1 to about 10 carbon atoms,and in one embodiment 1 to about 8 carbon atoms, and in one embodimentabout 2 to about 6 carbon atoms, and in one embodiment about 2 to about4 carbon atoms. These also include the akylene substituted aromaticcompounds containing one or more alkylene groups containing 2 to about20 carbon atoms, and in one embodiment 2 to about 18 carbon atoms, andin one embodiment 2 to about 16 carbon atoms, and in one embodiment 2 toabout 14 carbon atoms, and in one embodiment 2 to about 12 carbon atoms,and in one embodiment 2 to about 10 carbon atoms, and in one embodiment2 to about 8 carbon atoms, and in one embodiment about 2 to about 6carbon atoms, and in one embodiment about 2 to about 4 carbon atoms.Examples include toluene, o-xylene, m-xylene, p-xylene, hemimellitene,pseudocumene, mesitylene, prehnitene, isodurene, durene,pentamethylbenzene, hexamethylbenzene, ethylbenzene, n-propylbenzene,cumene, n-butylbenzene, isobutylbenzene, sec-butylbenzene,tert-butylbenzene, p-cymene, styrene, and the like.

The oxygen or oxygen source may comprise molecular oxygen, air or otheroxidants, such as nitrogen oxides, which can function as a source ofoxygen. The oxygen source may be carbon dioxide, carbon monoxide or aperoxide (e.g., hydrogen peroxide). Gaseous mixtures containing oxygen,such as mixtures of oxygen and air, or mixtures of oxygen and an inertgas (e.g., helium, argon, etc.) or a diluent gas (e.g., carbon dioxide,water vapor, etc.) may be used. The mole ratio of the hydrocarbonreactant to oxygen may range from about 0.2:1 to about 8:1, and in oneembodiment about 0.5:1 to about 4:1, and in one embodiment about 1:1 toabout 3:1. In one embodiment, the mole ratio is about 2:1 or higher, andin one embodiment about 2.5:1 or higher. In one embodiment, the moleratio is about 1.8 or less.

The ammonia may be obtained from any source. When used, the mole ratioof the hydrocarbon reactant to ammonia may range from about 0.5:1 toabout 5:1, and in one embodiment about 0.5:1 to about 2:1.

The catalyst may comprise any catalyst that is useful as an oxidation orammoxidation catalyst. The catalyst may comprise a metal, metal oxide ormixed metal oxide of a metal selected from Mo, W, V, Nb, Sb, Sn, Pt, Pd,Cs, Zr, Cr, Mg, Mn, Ni, Co, Ce, or a mixture of two or more thereof.These catalysts may also comprise one or more alkali metals or alkalineearth metals or other transition metals, rare earth metals, orlanthanides. Additionally elements such as P and Bi may be present. Thecatalyst may be supported, and if so, useful support materials includemetal oxides (e.g., alumina, titania, zirconia), silica, mesoporousmaterials, zeolites, refractory materials, or combinations of two ormore thereof.

The catalyst may comprise an oxidation catalyst represented by theformulaMo₁₂W_(a)Bi_(b)Fe_(c)Co_(d)Ni_(e)Si_(f)K_(g)Sn_(h)O_(x)in which: a is between 0 and 5, b is between 0.5 and 5, c is between 0.1and 10, d is between 0.5 and 10, e is between 0 and 10, f is between 0and 15, g is between 0 and 1, h is between 0 and 2, and x is thequantity of oxygen bonded to the other elements and depends on theiroxidation states. These catalysts are described in U.S. Pat. No.6,251,821 B1 as being useful for making acrolein from propylene byoxidation. This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMO_(a)Bi_(b)P_(c)X¹ _(d)X² _(e)X³ _(f)X⁴ _(g)O_(h)wherein X¹ is V, Nb, Ta, Cr, W, Ga, Ce and/or La; X² is Li, Na, K, Rb,Cs, Cu, Ag, Au, Pd and/or Pt; X³ is Sn, Pb, Sb, Bi, Te, Fe, Co and/orNi; X⁴ is Si, Al, Ti and/or Zr; a is 0 to 2; d is 0 to 2, with theproviso that the sum of a and d is at least 0.20; b is 0 to 1.5, c is 0to 10, with the proviso that the sum of b and c is at least 0.1; e is 0to 0.5, f is 0 to 0.5, g is 0 to 20 and h is a number different fromzero which is determined by the valence and frequency of the elementsdifferent from oxygen. This catalyst is disclosed in U.S. Pat. No.6,252,122 B1 as being useful for converting propane to acrolein. Thispatent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMo₁₂Bi_(a)Fe_(b)X_(c) ¹X_(d) ²X_(e) ³X_(f) ⁴O_(n)where X¹ is Ni and/or Co; X² is Tl, an alkali metal and/or an alkalineearth metal; X³ is Zn, P, As, B, Sb, Sn, Ce, Pb, and/or W; X⁴ is Si, Al,Ti and/or Zr; a is from 0.5 to 5; b is from 0.01 to 5, and in oneembodiment from 2 to 4; c is from 0 to 10, and in one embodiment from 3to 10; d is from 0 to 2, and in one embodiment from 0.02 to 2; e is from0 to 8, and in one embodiment from 0 to 5; f is from 0 to 10; and n is anumber which is determined by the valency and frequency of the elementsother than oxygen. These catalysts are disclosed in U.S. Pat. No.6,395,936 B1 as being useful for the oxidation of propylene to acrolein.This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformula[Bi_(n)A_(B)O_(x)][(100−z)%E_(e)Fe_(f)Ni_(g)Mo_(m)O_(y)+z %SiO₂]wherein A is at least one element selected from the group consisting ofB, P and Mo; E is at least one element having the atomic valence of 2;when m is 1, n is 0.001 to 3, a is 0 to 3, e is 0 to 3, f is 0.01 to 5,g is 0.1 to 5, and z is 0 to 90; and x and y are numbers such that thevalence requirements of the other elements for oxygen in the core andshell catalytic phase, respectively, are satisfied. This catalyst isdisclosed in U.S. Pat. No. 6,410,800 B1 as being useful for theoxidation of propylene to acrolein. This patent is incorporated hereinby reference.

The catalyst may comprise an oxidation catalyst represented by theformulaeMo₁₂Co_(3.5)Bi_(1.1)Fe_(0.8)W_(0.5)Si_(1.4)K_(0.05)O_(x)orNi_(2.1)Co_(3.5)Fe_(2.6)P_(0.43)Bi_(1.0)Mo_(9.3)Mn_(0.15)Cr_(00.9)Ba_(0.07)Zr_(0.0012)K_(0.07)O_(x)where x is the quantity of oxygen bonded to the other elements anddepends on their oxidation state. These catalysts are disclosed in U.S.Pat. No. 6,437,193 B1 as being useful for the oxidation of propylene toacrolein. This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaBi_(b)MO_(c)V_(v)A_(B)D_(d)E_(e)O_(x)wherein A is one or more of K, Na, Li, Cs and Tl; D is one or more ofFe, Ni, Co, Zn, Ce or La; E is one or more of W, Nb, Sb, Sn, P, Cu, Pb,B, Mg, Ca or Sr; a, d and e are each 0 to 10; b is 0.1 to 10; c is 0.1to 20; v is 0.1 to 10; c:b is from 2:1 to 30:1; v:b is from 1.5 to 8:1;and x is determined by the frequency and the valence of the elementsother than oxygen in the above formula. This catalyst is disclosed inU.S. Pat. No. 5,198,580 as being useful for the conversion of propane toacrylic acid, propylene, acrolein and acetic acid.

The catalyst may comprise an oxidation catalyst represented by theformulaM¹ _(a)Mo_(1-b)M² _(b)O_(x)where M¹ is Co, Ni, Mg, Zn, Mn and/or Cu; M² is W, V, Te, Nb, P, Cr, Fe,Sb, Ce, Sn and/or La; a is from 0.5 to 1.5, b is from 0 to 0.5; and x isa number which is determined by the valency and frequency of theelements other than oxygen. These catalysts are disclosed in U.S. Pat.Nos. 6,388,129 B1; 6,423,875 B1; and 6,426,433 B1 as being useful forthe conversion of propane to acrolein and/or acrylic acid. These patentsare incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaA_(a)B_(b)C_(c)Ca_(d)Fe_(e)Bi_(f)Mo₁₂O_(x)where A is one or more of Li, Na, K, Rb or Cs; B is one or more of Mg,Sr, Mn, Ni, Co or Zn; C is one or more of Ce, Cr, Al, Sb, P, Ge, Sn, Cu,V or W; a is 0.01 to 1.0; b and e are 1.0 to 10; c is 0 to 5.0, and inone embodiment 0.05 to 5.0, and in one embodiment 0.05 to 4.0; d and fare 0.05 to 5.0; and x is a number determined by the valencerequirements of the other elements present. These catalysts aredisclosed in U.S. Pat. No. 6,268,529 B1 as being useful for theconversion of propane to acrolein and acrylic acid. This patent isincorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMo12 V_(4.8) Sr_(0.5) W_(2.4) Cu_(2.2) O_(x)where x is the quantity of oxygen bonded to the other elements anddepends on their oxidation state. This catalyst is disclosed in U.S.Pat. No. 6,310,240 B1 as being useful in the conversion of acrolein toacrylic acid. This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMO_(a)W_(b)V_(c)A_(d)B_(e)O_(x)wherein A is Fe, Cu, Bi, Cr, Sn, Sb, Ni, Co, Mn, Ce or Tl; B is analkali or alkaline earth metal; and a, b, c, d, e and x respectivelyindicate the atomic ratio for Mo, W, V, A, B and O. When a is 10, b is1.5 to 4, c is 1 to 5, d is 1 to 4, e is 0 to 2, and x is determinedaccording to oxidation states of the other elements. This catalyst isdisclosed in U.S. Pat. No. 6,384,275 B2 as being useful for theconversion of acrolein to acrylic acid. This patent is incorporatedherein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMo12 V_(a) X¹ _(b) X² _(c) X³ _(d) X⁴ _(e) X⁵ _(f) X⁶ _(g)O_(n)where X¹ is W, Nb, Ta, Cr and/or Ce; X² is Cu, Ni, Co, Fe, Mn and/or Zn;X³ is Sb and/or Bi; X4 is one or more alkali metals; X⁵ is one or morealkaline earth metals; X⁶ is Si, Al, Ti and/or Zr; a is from 1 to 6; bis from 0.2 to 4; c is from 0.5 to 18; d is from 0 to 40; e is from 0 to2; f is from 0 to 4; g is from 0 to 40 and n is a number which isdetermined by the valency and frequency of the elements other thanoxygen. This catalyst is disclosed in U.S. Pat. No. 6,403,829 B2 asbeing useful for the conversion of acrolein to acrylic acid. This patentis incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMO_(a)V_(b)W_(c)Cu_(d)X_(e)O_(g)wherein X is at least one element selected from the group consisting ofMg, Ca, Sr and Ba, and a, b, c, d, e, and g are atomic ratiosrespectively of Mo, V, W, Cu, X and O such that when a is 12, b is inthe range of 2 to 14, c in the range of 0 to 12, d in the range of 0 to6 excluding 0 (0.1 to 6, for example), e is in the range of 0 to 3, andg is a numeral to be determined by the oxidized states of the elements.This catalyst is disclosed in U.S. Pat. No. 6,429,332 B1 as being usefulfor the conversion of acrolein to acrylic acid. This patent isincorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMo_(a)W_(b)Bi_(c)Fe_(d)A_(e)B_(f)C_(g)D_(h)E_(i)O_(x)wherein: A is Ni or Co; B is Na, K, Rb, Cs or Tl; C is an alkaline earthmetal; D is P, Te, Sb, Sn, Ce, Pb, Nb, Mn, As, B or Zn; and E is Si, Al,Ti or Zr. When a is 12, b is from 0 to 10, c is from 0 to 10, d is from0 to 10, e is from 2 to 15, f is from 0 to 10, g is from 0 to 10, h isfrom 0 to 4, i is from 0 to 30, and x is determined by the degree ofoxidation of each of the elements. This catalyst is disclosed in U.S.Pat. No. 6,383,973 B1 as being useful for the conversion of propylene,isobutylene, t-butanol or methyl-t-butyl ether to (meth)acrolein or(meth)acrylic acid. This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst represented by theformulaMO_(a)P_(b)A_(c)B_(a)C_(e)D_(f)O_(x)wherein A is at least one element selected from the group consisting ofAs, Sb, Ge, Bi, Zr, Ce and Se; B is at least one element selected fromthe group consisting of Cu, Fe, Cr, Ni, Mn, Co, Sn, Ag, Zn, Pd, Rh andTe; C is at least one element selected from the group consisting of V, Wand Nb; D is at least one element selected from the group consisting ofalkali metals, alkaline earth metals and Tl, and a, b, c, d, e, f, and xare atomic ratios respectively of Mo, P, A, B, C, D, and O such thatwhen a is 12, b is a numeral in the range of 0.5 to 4, and in oneembodiment 0.5 to 3; c is in the range of 0 to 5, and in one embodiment0.01 to 3; d in the range of 0 to 3, and in one embodiment 0.01 to 2; eis in the range or 0 to 4, and in one embodiment 0.01 to 3; f is in therange or 0.01 to 4, and in one embodiment 0.01 to 3, and x is a numeralto be determined by the oxidized states of the elements. This catalystis disclosed in U.S. Pat. No. 5,618,974 as being useful for theconversion of methacrolein, isobutyl aldehyde, or isobutyric acid tomethacrylic acid. This patent is incorporated herein by reference.

The catalyst may comprise an oxidation catalyst containing Mo, V, Nb andPd, or Mo, La, V and Pd. Specific examples includeMoV_(0.396)Nb_(0.128)Pd_(0.000384)andMoV_(0.628)Pd_(0.000288)La_(0.00001)These catalysts are disclosed in U.S. Pat. No. 6,274,764 B1, which isincorporated herein by reference.

U.S. Pat. No. 6,143,921, which is incorporated herein by reference,discloses three oxidation catalysts, any one of which may be used withthe inventive process. The first catalyst is represented by the formulaMo_(a)V_(b)Nb_(c)Pd_(d), wherein: a is 1 to 5; b is 0 to 0.5; c is 0.01to 0.5; and d is 0 to 0.2. The numerical values of a, b, c and drepresent the relative gram-atom ratios of the elements Mo, V, Nb andPd, respectively, in the catalyst. The elements are present incombination with the oxygen in the form of various oxides. The secondcatalyst has a composition comprising the elements Mo, V, Pd, Nb, La,and X where X is Al, Ga, Si or Ge in the form of oxides in the ratioMo_(a)V_(b)La_(c)Pd_(d)Nb_(e)X_(f) wherein: a is 1; b is 0.01 to 0.9; cis >0 to 0.2; d is >0 to 0.2; e is >0 to 0.2; and f is >0 to 0.3. Thethird catalyst is formed from a calcined composition represented by theformula Mo_(a)V_(b)Nb_(c)X_(d), wherein X is at least one promoterelement selected from the group consisting of: P, B, Hf, Te and As; a isabout 1 to 5; b is 1; c is about 0.01 to 0.5; and d is about 0 to 0.1.

The catalyst may be an oxidation catalyst which comprises in combinationwith oxygen the elements molybdenum, vanadium, niobium and goldaccording to the formula:Mo_(a)W_(b)Au_(c)V_(d)Nb_(e)Y_(f)wherein: Y is one or more elements selected from the group consisting ofCr, Mn, Ta, Ti, B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag,Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn,Tl, U, Re, Te, La and Pd; a, b, c, d, e and f represent the gram atomratios of the elements such that 0<a≦1; 0≦b<1; a+b=1; 10⁻⁵<c≦0.02;0<d≦2; 0<e≦1; and 0<f≦2. This catalyst is disclosed in U.S. Pat. No.6,333,444 B1 as being useful for the oxidation of ethane or ethylene toacetic acid. This patent in incorporated herein by reference.

The catalyst may be an oxidation catalyst having a calcined compositionrepresented by the formula Mo_(a)V_(b)Nb_(c)Pd_(d), wherein: 1 is 1 to5; b is 0 to 0.5; c is 0.01 to 0.5; and d is 0 to 0.2. This catalyst isdisclosed in U.S. Pat. No. 6,383,977 B1 for converting ethane to aceticacid. This patent is incorporated herein by reference.

U.S. Pat. No. 6,441,227 B1, which is incorporated herein by reference,discloses two oxidation catalysts which can be used separately or incombination with each other in the inventive process. The first catalystis a mixed metal oxide represented by formulaMo_(a)Pd_(b)Bi_(c)Fe_(d)X¹ _(e)X² _(f)X³ _(g)O_(z)wherein: X¹ is at least one or more of Co, Ni, V, Pt or Rh; X² is atleast one or more of Al, Ga, Ge, Mn, Nb, Zn, Ag, P, Si or W; X³ is atleast one or more of K, Mg, Rb, Ca, Sr, Ba, Na or In; O is oxygen, and ais 1; 0<b≦0.3; 0<c≦0.9; 0<d≦0.9; 0<e≦0.9; 0<f≦0.9; 0<g≦0.3; and z is anumber which satisfies the valences of the other elements in theformula. This catalyst is described as being useful for convertingolefins to alpha-beta unsaturated aldehydes. The second catalyst is ametal oxide represented by the formulaMo_(a1)V_(b1)Al_(c1)X_(d1)Y_(e1)O_(z1)wherein X is W or Mn or both; Y is at least one or more of Pd, Sb, Ca,P, Ga, Ge, Si, Mg, Nb or K; O is oxygen, and a₁ is 1; b₁ is 0.01 to 0.9;0<c₁≦0.2; 0<d₁≦0.5; 0<e₁≦0.5; and z, is a number which satisfies thevalences of the other elements in the formula. This catalyst isdescribed as being suitable for converting an alpha-beta unsaturatedaldehyde to an alpha-beta unsaturated carboxylic acid.

The catalyst may comprise an ammoxidation catalyst represented by theformulaA_(a)K_(b)Cs_(c)Mg_(d)Ni_(e)Fe_(f)Bi_(g)Mo₁₂O_(x)wherein A is one or more of the elements selected from Co, Mn, Cr, P,Sb, Te, Na, Ce or W, a is a number from 0 to 5; b is a number from 0 to0.4; c is a number from 0 to 0.4, provided that the sum of b and c isfrom 0.1 to 0.4; d, e, f, and g are numbers from about 0.2 to 10, and xis a number determined by the valence requirements of the otherelements. This catalyst is disclosed in U.S. Pat. No. 5,093,299 as beinguseful for the conversion of an olefin (e.g., propylene or isobutylene)to the corresponding unsaturated nitrile (e.g., acrylonitrile ormethacrylonitrile) by reacting the olefin, ammonia and oxygen in thepresence of the foregoing catalyst. This patent is incorporated hereinby reference.

The catalyst may comprise an ammoxidation catalyst represented by theformulaVSb_(a)M_(m)N_(n)O_(x)where a is 0.5 to 2; M is one or more of Sn, Ti, Fe or Ga; m is 0.05 to3; N is one or more of: W, Bi, Mo, Li, Mg, P, Zn, Mn, Te, Ge, Nb, Zr,Cr, Al, Cu, Ce or B; n is 0.0 to 0.5; and x is a number determined bythe degree of oxidation of each of the other elements. This catalyst isdisclosed in U.S. Pat. No. 5,258,543 as being useful for theammoxidation of C₃ to C₅ monoolefins to alpha, beta-monounsaturatedacyclic nitriles (e.g., acrylonitrile) having 3 to 5 carbon atoms.

U.S. Pat. No. 6,486,091 B1, which is incorporated herein by reference,discloses an ammoxidation catalyst represented by the formulaBi_(a)Mo_(b)V_(c)Sb_(d)Nb_(e)A_(f)B_(g)O_(x)wherein: A is one or more elements selected from groups VB (e.g., V, Nb,Ta), VIB (e.g., Cr, Mo, W), VIIB (e.g., Mn, Tc, Re) or VIII (e.g., Fe,Co, Ni) of the periodic table; B is at least one alkali promoterselected from groups IA (e.g., Li, Na, K) or IIA (e.g., Mg, Ca) of theperiodic table; a is 0.01 to 12; b is 0.01 to 12; c is 0.01 to 2; d is0.01 to 10; e is 0.01 to 1; f is 0 to 2; g is 0 to 1; and x is thenumber of oxygen atoms required to satisfy the valency requirements ofthe elements present. This catalyst is described as being useful forconverting olefins to unsaturated nitrites.

In one embodiment, the catalyst is other than a vanadium phosphorusoxide based catalyst. In one embodiment the catalyst is other than acatalyst represented by the formula V₂O₅/P₂O₅/TiO₂.

The catalyst may have any size and geometric configuration that fitswithin the process microchannels 104. The catalyst may be in the form ofparticulate solids (e.g., pellets, powder, fibers, and the like) havinga median particle diameter of about 1 to about 1000 μm, and in oneembodiment about 10 to about 500 μm, and in one embodiment about 25 toabout 250 μm. The catalyst may be comprised of a porous structure suchas a foam, felt, wad or a combination thereof. The term “foam” is usedherein to refer to a structure with continuous walls defining poresthroughout the structure. The term “felt” is used herein to refer to astructure of fibers with interstitial spaces therebetween. The term“wad” is used herein to refer to a structure of tangled strands, likesteel wool. The catalyst may have a honeycomb structure, or thestructure of an insertable fin. The fin may have straight channels ormay take the form of an offset strip fin. The number of fins per inchmay range from about 4 to about 90. The fins may have a thickness ofabout 0.02 to about 2.5 mm.

The catalyst may be in the form of a flow-by structure such as a feltwith an adjacent gap, a foam with an adjacent gap, a fin structure withgaps, a washcoat on any inserted substrate, or a gauze that is parallelto the flow direction with a corresponding gap for flow. An example of aflow-by structure is illustrated in FIG. 5. In FIG. 5, the catalyst 106is contained within process microchannel 104. An open passage way 500permits the flow of fluid through the process microchannel 104 incontact with the catalyst 106 as indicated by arrows 502 and 504.

The catalyst may be in the form of a flow-through structure such as afoam, wad, pellet or powder, or gauze. An example of a flow-throughstructure is illustrated in FIG. 6. In FIG. 6, the flow-through catalyst106 is contained within process microchannel 104 and the fluid flowsthrough the catalyst 106 as indicated by arrows 600 and 602.

The catalyst may be directly washcoated on the interior walls of theprocess microchannels, grown on the walls from solution, or coated insitu on a fin structure. The catalyst may be in the form of a singlepiece of porous contiguous material, or many pieces in physical contact.In one embodiment, the catalyst is comprised of a contiguous materialand has a contiguous porosity such that molecules can diffuse throughthe catalyst. In this embodiment, the fluids flow through the catalystrather than around it. In one embodiment, the cross-sectional area ofthe catalyst occupies about 1 to about 99%, and in one embodiment about10 to about 95% of the cross-sectional area of the processmicrochannels. The catalyst may have a surface area, as measured by BET,of greater than about 0.5 m²/g, and in one embodiment greater than about2 m²/g.

The catalyst may comprise a porous support, an interfacial layer on theporous support, and a catalyst material on the interfacial layer. Theinterfacial layer may be solution deposited on the support or it may bedeposited by chemical vapor deposition or physical vapor deposition. Inone embodiment the catalyst has a porous support, a buffer layer, aninterfacial layer, and a catalyst material. Any of the foregoing layersmay be continuous or discontinuous as in the form of spots or dots, orin the form of a layer with gaps or holes.

The catalyst may be supported on a porous substrate having a porosity ofat least about 5% as measured by mercury porosimetry and an average poresize (sum of pore diameters divided by number of pores) of about 1 toabout 1000 μm. The porous support may be a porous ceramic or a metalfoam. Other porous supports that may be used include carbides, nitrides,and composite materials. The porous support may have a porosity of about30% to about 99%, and in one embodiment about 60% to about 98%. Theporous support may be in the form of a foam, felt, wad, or a combinationthereof. The open cells of the metal foam may range from about 20 poresper inch (ppi) to about 3000 ppi, and in one embodiment about 20 toabout 1000 ppi, and in one embodiment about 40 to about 120 ppi. Theterm “ppi” refers to the largest number of pores per inch (in isotropicmaterials the direction of the measurement is irrelevant; however, inanisotropic materials, the measurement is done in the direction thatmaximizes pore number).

The buffer layer, when present, may have a different composition and/ordensity than both the support and the interfacial layers, and in oneembodiment has a coefficient of thermal expansion that is intermediatethe thermal expansion coefficients of the porous support and theinterfacial layer. The buffer layer may be a metal oxide or metalcarbide. The buffer layer may be comprised of Al₂O₃, TiO₂, SiO₂, ZrO₂,or combination thereof. The Al₂O₃ may be α-Al₂O₃, γ-Al₂O₃ or acombination thereof. α-Al₂O₃ provides the advantage of excellentresistance to oxygen diffusion. The buffer layer may be formed of two ormore compositionally different sublayers. For example, when the poroussupport is metal, for example a stainless steel foam, a buffer layerformed of two compositionally different sub-layers may be used. Thefirst sublayer (in contact with the porous support) may be TiO₂. Thesecond sublayer may be α-Al₂O₃ which is placed upon the TiO₂. In oneembodiment, the α-Al₂O₃ sublayer is a dense layer that providesprotection of the underlying metal surface. A less dense, high surfacearea interfacial layer such as alumina may then be deposited as supportfor a catalytically active layer.

The porous support may have a thermal coefficient of expansion differentfrom that of the interfacial layer. In such a case a buffer layer may beneeded to transition between the two coefficients of thermal expansion.The thermal expansion coefficient of the buffer layer can be tailored bycontrolling its composition to obtain an expansion coefficient that iscompatible with the expansion coefficients of the porous support andinterfacial layers. The buffer layer should be free of openings and pinholes to provide superior protection of the underlying support. Thebuffer layer may be nonporous. The buffer layer may have a thicknessthat is less than one half of the average pore size of the poroussupport. The buffer layer may have a thickness of about 0.05 to about 10μm, and in one embodiment about 0.05 to about 5 μm.

In one embodiment of the invention, adequate adhesion and chemicalstability may be obtained without a buffer layer. In this embodiment thebuffer layer may be omitted.

The interfacial layer may be comprised of nitrides, carbides, sulfides,halides, metal oxides, carbon, or a combination thereof. The interfaciallayer provides high surface area and/or provides a desirablecatalyst-support interaction for supported catalysts. The interfaciallayer may be comprised of any material that is conventionally used as acatalyst support. The interfacial layer may be comprised of a metaloxide. Examples of metal oxides that may be used include γ-Al₂O₃, SiO₂,ZrO₂, TiO₂, tungsten oxide, magnesium oxide, vanadium oxide, chromiumoxide, manganese oxide, iron oxide, nickel oxide, cobalt oxide, copperoxide, zinc oxide, molybdenum oxide, tin oxide, calcium oxide, aluminumoxide, lanthanum series oxide(s), zeolite(s) and combinations thereof.The interfacial layer may serve as a catalytically active layer withoutany further catalytically active material deposited thereon. Usually,however, the interfacial layer is used in combination with acatalytically active layer. The interfacial layer may also be formed oftwo or more compositionally different sublayers. The interfacial layermay have a thickness that is less than one half of the average pore sizeof the porous support. The interfacial layer thickness may range fromabout 0.5 to about 100 μm, and in one embodiment from about 1 to about50 μm. The interfacial layer may be either crystalline or amorphous. Theinterfacial layer may have a BET surface area of at least about 1 m²/g.

The catalyst may comprise any of the catalyst materials discussed abovedeposited on the interfacial layer. Alternatively, the catalyst materialmay be simultaneously deposited with the interfacial layer. The catalystlayer may be intimately dispersed on the interfacial layer. That thecatalyst layer is “disposed on” or “deposited on” the interfacial layerincludes the conventional understanding that microscopic catalystparticles are dispersed: on the support layer (i.e., interfacial layer)surface, in crevices in the support layer, and in open pores in thesupport layer.

The contact time of the reactants and/or products with the catalyst 106within the process microchannels 104 may range from about 0.1 ms toabout 100 seconds, and in one embodiment about 0.1 ms to about 20seconds, and in one embodiment about 0.1 ms to about 10 seconds, and inone embodiment about 0.1 ms to about 5 seconds, and in one embodimentabout 0.1 ms to about 1 second, and in one embodiment from about 1 ms toabout 750 ms, and in one embodiment about 5 ms to about 750 ms, and inone embodiment about 10 to about 500 ms, and in one embodiment about 10to about 250 ms.

The space velocity (or gas hourly space velocity) for the flow of thereactant composition and product through the process microchannels maybe at least about 100 hr¹ (normal liters of hydrocarbon/hour/liter ofreaction chamber) or at least about 100 ml feed/(g catalyst) (hr). Thespace velocity may range from about 100 to about 2,000,000 hr⁻¹ based onthe volume of the process microchannels, or from about 100 to about2,000,000 ml feed/(g catalyst) (hr). In one embodiment, the spacevelocity may range from about 500 to about 1,000,000 hr⁻¹, or about 500to about 1,000,000 ml feed/(g catalyst) (hr), and in one embodiment fromabout 1000 to about 1,000,000 hr⁻¹, or from about 1000 to about1,000,000 ml feed/(g catalyst) (hr).

The temperature of the reactant composition entering the processmicrochannels 104 may range from about 150° C. to about 1000° C., and inone embodiment about 150° C. to about 700° C., and in one embodimentabout 150° C. to about 600° C., and in one embodiment about 200° C. toabout 600° C. In one embodiment the temperature may be in the range ofabout 150° C. to about 500° C., and in one embodiment about 150° C. toabout 400° C., and in one embodiment about 200° C. to about 300° C. Inone embodiment, the temperature may be in the range of about 335° C. toabout 1000° C.

The reactant composition entering the process microchannels 104 may beat a pressure of at least about 0.5 atmosphere, and in one embodiment atleast about 0.9 atmosphere. In one embodiment the pressure may rangefrom about 0.5 to about 100 atmospheres, and in one embodiment fromabout 0.9 to about 50 atmospheres, and in one embodiment about 0.9 toabout 40 atmospheres, and in one embodiment from about 0.9 to about 35atmospheres.

The pressure drop of the reactants and/or products as they flow throughthe process microchannels 104 may range up to about 30 pounds per squareinch per foot of length of the process microchannel (psi/ft), and in oneembodiment up to about 15 psi/ft, and in one embodiment up to 5 psi/ft,and in one embodiment up to about 2 psi/ft.

The flow of the reactants and/or products through the processmicrochannels may be laminar or in transition, and in one embodiment itis laminar. The Reynolds Number for the flow of reactants and/orproducts through the process microchannels may be up to about 4000, andin one embodiment up to about 2300, and in one embodiment in the rangeof about 10 to about 2000, and in one embodiment about 100 to about1500.

The heat exchange fluid entering the heat exchange channels may have atemperature of about −70° C. to about 650° C., and in one embodimentabout 0° C. to about 500° C., and in one embodiment about 100° C. toabout 300° C. The heat exchange fluid exiting the heat exchange channelsmay have a temperature in the range of about −60° C. to about 630° C.,and in one embodiment about 10° C. to about 490° C. The residence timeof the heat exchange fluid in the heat exchange channels may range fromabout 1 to about 1000 ms, and in one embodiment about 1 to about 500 ms,and in one embodiment from 1 to about 100 ms. The pressure drop for theheat exchange fluid as it flows through the heat exchange channels mayrange from about 0.05 to about 50 psi/ft, and in one embodiment fromabout 1 to about 25 psi/ft. The flow of the heat exchange fluid throughthe heat exchange channels may be laminar or in transition, and in oneembodiment it is laminar. The Reynolds Number for the flow of heatexchange fluid flowing through the heat exchange channels may be up toabout 4000, and in one embodiment up to about 2300, and in oneembodiment in the range of about 10 to about 2000, and in one embodimentabout 10 to about 1500.

The product exiting the microchannel reactor may be at a temperature inthe range of about 100° C. to about 1000° C., and in one embodimentabout 200° C. to about 800° C., and in one embodiment about 300° C. toabout 600° C.; and during step (C) it may be cooled to a temperature inthe range of about 50° C. to about 300° C., and in one embodiment about50° C. to about 200° C., and in one embodiment about 50° C. to 150° C.,and in one embodiment about 50° C. to about 100° C., in about 5 to about100 ms, and in one embodiment about 5 to about 75 ms, and in oneembodiment about 5 to about 50 ms, and in one embodiment about 10 toabout 50 ms.

The product formed by the inventive process may comprise an oxygenate ora nitrile. The oxygenates include alcohols, epoxides, aldehydes,carboxylic acids, carboxylic acid anhydrides, esters, and the like. Theoxygenates include, with the exception of the epoxides and esters, oneor more of the above-indicated oxygenates containing 1 to about 20carbon atoms per molecule, and in one embodiment 1 to about 18 carbonatoms, and in one embodiment 1 to about 16 carbon atoms, and in oneembodiment 1 to about 14 carbon atoms, and in one embodiment 1 to about12 carbon atoms, and in one embodiment 1 to about 10 carbon atoms, andin one embodiment about 2 to about 6 carbon atoms, and in one embodimentabout 2 to about 4 carbon atoms per molecule. The epoxides and estersmust contain at least 2 carbon atoms, but in all other respects wouldinclude compounds within the above-indicated ranges, for example, 2 toabout 20 carbon atoms, etc. The alcohols include monools and polyols.Specific examples include methanol, ethyl alcohol, propyl alcohol, butylalcohol, isobutyl alcohol, pentyl alcohol, cyclopentyl alcohol, crotylalcohol, hexyl alcohol, cyclohexyl alcohol, allyl alcohol, benzylalcohol, glycerol, and the like. The epoxides include ethylene oxide,propylene oxide, butylene oxide, isobutylene oxide, cyclopentene oxide,cyclohexene oxide, styrene oxide, and the like. The aldehydes includeformaldehyde; acetaldehyde; propionaldehyde; n-butyraldehyde;n-valeraldehyde; caproaldehyde; acrolein; tran-2-cis-6-nonadienal;n-heptylaldehyde; trans-2-hexenal; hexadeconal; benzaldehyde;phenylacetaldehyde; o-tolualdehyde; m-tolualdehyde; p-tolualdehyde;salicylaldehyde; p-hydroxybenzaldehyde; and the like. The carboxylicacids include formic acid, acetic acid, propionic acid, butyric acid,isobutyric acid, valeric acid, caproic acid, caprylic acid, capric acid,acrylic acid, methacrylic acid, benzoic acid, toluic acid, phthalicacid, salicylic acid, and the like. The carboxylic acid anhydridesinclude acetic anhydride, maleic anhydride, phthalic anhydride, benzoicanhydride, and the like. The esters include methyl acetate, vinylacetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-pentylacetate, isopentyl acetate, benzyl acetate, phenyl acetate, and thelike.

The nitriles include those containing 1 to about 20 carbon atoms, and inone embodiment 1 to about 18 carbon atoms, and in one embodiment 1 toabout 16 carbon atoms, and in one embodiment 1 to about 14 carbon atoms,and in one embodiment 1 to about 12 carbon atoms, and in one embodiment1 to about 10 carbon atoms, and in one embodiment 1 to about 8 carbonatoms, and in one embodiment 2 to about 6 carbon atoms, and in oneembodiment 3 or 4 carbon atoms per molecule. These nitrites includeunsaturated nitrites. Specific examples include formonitrile,acrylonitrile, methacrylonitrile, and the like.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises methane, and the product comprises methanol,formaldehyde, formonitrile, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises ethane, and the product comprises ethyl alcohol,ethylene oxide, acetic acid, vinyl acetate, or a mixture of two or morethereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises ethylene, and the product comprises ethyl alcohol,ethylene oxide, acetic acid, vinyl acetate, or a mixture of two or morethereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises propane, and the product comprises propyleneoxide, acrylic acid, acrolein, acrylonitrile, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises propylene, and the product comprises propyleneoxide, acrylic acid, acrolein, acrylonitrile, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises n-butane, and the product comprises n-butanol,maleic anhydride, or a mixture of two or more thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises n-butene, and the product comprises n-butanol,maleic anhydride, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises isobutane, and the product comprises isobutanol,methacrylic acid, methacrylonitrile, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises isobutylene, and the product comprises isobutanol,methacrylic acid, methacrylonitrile, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises cyclopentene, and the product comprisescyclopentene oxide.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises cyclohexene, and the product comprises cyclohexeneoxide.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises styrene, and the product comprises styrene oxide.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises toluene, and the product comprises benzyl alcohol,benzaldehyde, benzoic acid, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises xylene, and the product comprises toluic acid,phthalic acid, phthalic anhydride, or a mixture thereof.

In one embodiment, the hydrocarbon reactant used in the reactantcomposition comprises acrolein and the product comprises acrylic acid.

Advantages of the inventive process include: maximization of contactbetween the hydrocarbon reactant, oxygen or source of oxygen, andoptionally ammonia, and the catalyst; and minimization of homogenousgas-phase unselective reactions, such as those which convert hydrocarbonreactants or oxygenate or nitrile products to carbon oxides (CO andCO₂). In one embodiment, selectivity to carbon oxides (on a carbon atombasis) is less than about 60%, and in one embodiment less than about40%, and in one embodiment less than about 20%, and in one embodimentless than about 10%, and in one embodiment less than about 5%.

Advantages of the inventive process include the possibility of processintensification. Conventional processes of the prior art often operateunder conditions of reactant dilution to prevent runaway reactions,while the inventive process may be operated, if desired, under moreintensive conditions leading to greater throughput. By combiningcatalytic microchannel processing with heat exchange it is possible tooperate at hydrocarbon feed/oxygen ratios that would conventionally leadto high temperatures and loss of selectivity, but by removing heatrapidly through heat exchange, the temperature in the processmicrochannels may be maintained relatively low, for example, below about700° C., and in one embodiment below about 600° C., and in oneembodiment below about 500° C., thus maximizing selectivity to desiredproducts.

Advantages of the inventive process include the enhancement of reactionselectivity due to the dimensions of the microchannel reactor. Inreactors of conventional dimension, reactions propagated homogeneouslyin the in the gaseous phase make a significant contribution to theoverall make-up of the product. These reactions tend to beindiscriminate and often result in the production of undesirableby-products such as CO and CO₂ or hydrocarbon pyrolysis products. Forexample, if the reactant mixture contains propane, full and partialoxidation can take place as well as pyrolysis leading to the productionof ethane and methane. Significant increases in reaction selectivity tothe oxygenate or nitrile product can be achieved when conducted in amicrochannel reactor in accordance with the invention wherein themicrochannel reactor has an internal height or width at or near thequench diameter for the reaction in question.

The level of conversion of the hydrocarbon reactant may be about 10% orhigher, and in one embodiment about 50% or higher, and in one embodimentabout 75% or higher, and in one embodiment about 90% or higher.

The level of selectivity of the desired product may be about 40% orhigher, and in one embodiment about 50% or higher, and in one embodimentabout 60% or higher, and in one embodiment about 70% or higher, and inone embodiment about 80% or higher, and in one embodiment about 85% orhigher, and in one embodiment about 90% or higher, and in one embodimentabout 95% or higher. In one embodiment, the level of selectivity to thedesired product may be in the range of about 50% to about 95%, and inone embodiment about 75% to about 95%.

The yield of the desired product may be about 40% or higher per cycle,and in one embodiment about 50% or higher, and in one embodiment about60% or higher, and in one embodiment about 70% or higher per cycle, andin one embodiment about 80% or higher, and in one embodiment 85% orhigher, and in one embodiment about 90% or higher per cycle. The term“cycle” is used herein to refer to a single pass of the reactantsthrough the process microchannels.

In one embodiment, the level of conversion of the hydrocarbon reactantis at least about 95%, the level of selectivity of the desired productis at least about 95%, and the yield of the desired product is at leastabout 90% per cycle.

In one embodiment, the process is conducted in a reactor containing aplurality of heat exchange channels operating in parallel, the totalpressure drop for the heat exchange fluid flowing through the heatexchange channels is up to about 10 atmospheres, and in one embodimentup to about 5 atmospheres, and in one embodiment up to about 2atmospheres.

In one embodiment, the thermal efficiency of the heat exchange used inthe microchannel reactor is sufficient for the temperature of theexiting product stream (e.g., product stream 130 in FIG. 1 or productstream 320 in FIG. 3A) to be within about 1000C of the temperature ofthe entering reactant stream and/or oxidant stream (e.g., reactantstream 120 and/or oxidant stream 122 in FIG. 1, or reactant stream 316and/or oxidant stream 318 in FIG. 3A), and in one embodiment withinabout 75° C., and in one embodiment within about 50° C., and in oneembodiment within about 25° C., and in one embodiment within about 10°C.

Unlike conventional reaction vessels for oxidations and ammoxidationswhich have to take into account the possibility of explosions formixtures of oxygen and hydrocarbon, the possibility of such explosionswith the inventive process is of less concern. This is believed to bedue to the relatively brief catalyst contact times employed in theprocess microchannels, the added cooling provided by Step (B) of theprocess, and the dimensions of the microchannels which make themeffective flame arresters preventing the propagation of combustionreactions and flames that would normally lead to explosions and/ordetonations. Thus, with the inventive process it is permissible tooperate at least partly in the explosion range without incurring anexplosion.

EXAMPLES 1-8

In the following Examples 1-8, the reaction process illustrated in FIGS.3A and 3B is used. The microchannel reactor 300 is fabricated from sixdistinct pieces: microchannel reactor core 301, reactant header 302,oxidant header 304, product footer 306, heat exchange header 310 andheat exchange footer 312. Each piece is fabricated from 316 stainlesssteel. Alternatively, other steel alloys, Inconel 617 or other nickelalloys, FeCrAlY or other high temperature alloys could be used. Thereactant header, oxidant header and product footer have a common designand construction. The heat exchange header and heat exchange footer havea common design and construction. The headers and footers are formed bymachining a pocket in a solid block using an end mill. Alternatively,the headers and footers could be fabricated via welding from standardpipe, or any method that is suitable to the material of construction andoverall size of the device including stacking and bonding laminatesheets.

The microchannel reactor core 301 is fabricated using microcomponentsheet architecture. The microchannel reactor core 301 contains twozones, reactor zone 307, and manifold and recuperator zone 308. Thesezones are differentiated primarily by the fact that in the reactor zone307 heat exchange microchannels 380 and 390 run in alternating planes tothe oxidant microchannels 360 and process microchannels 340 and 350. Thecatalyst is present in the process microchannels 340 and 350 in thereaction zone 307 in the form of a packed bed of powder. Alternatively,the catalyst could be in the form of a foam, felt, wad or washcoatedinsert. The catalyst could be directly washcoated on the interior wallsof the process microchannels 340 and 350.

The microchannel core reactor 301 is assembled by joining together allof the microcompent sheets via diffusion bonding. Alternatively, thesheets could be joined via diffusion brazing, brazing, laser welding orother suitable techniques. The reactant header 302, oxidant header 304,product footer 306 and heat exchange header 310 and heat exchange footer312 are attached to the microchannel core reactor 301 by welding orbrazing. Alternatively, the reactant header, oxidant header, productfooter and the heat exchange header and footer may be attached to themicrochannel core reactor during the joining step.

The reactant composition comprising the hydrocarbon reactant, andoptionally ammonia, flows into the microchannel reactor 300 through thereactant header 302, as indicated by directional arrow 316. The oxygenor source of oxygen flows into the microchannel reactor 300 through theoxidant header 304 as indicated by directional arrow 318. Thehydrocarbon reactant, oxygen or source of oxygen, and optionallyammonia, flow into and through the manifold and recuperator 308 into thereactor zone 307 wherein they contact the catalyst and react to form thedesired product. The product flows from the reactor zone 307 through aninternal manifold to recuperator 308, where product quench may occur,then to product footer 306, and from product footer 306, optionallythrough quenching apparatus 314, as indicated by directional arrows 320and 322. A heat exchange fluid flows into heat exchange header 310, asindicated by directional arrow 324, and then from heat exchange header310 through microchannel reactor core 301 to heat exchange footer 312,and then out of heat exchange footer 312, as indicated by directionalarrow 326. Within the microchannel reactor core 301, the oxygen orsource of oxygen is added to the hydrocarbon reactant, and optionallyammonia, using staged addition as illustrated in FIG. 3B and discussedabove.

Example 1

The hydrocarbon reactant is ethylene. The source of oxygen is air. Theoxygen is mixed with the ethylene using staged addition, the volumetricratio of air to ethylene when fully mixed being 86:14. The catalyst isan oxidation catalyst. The heat exchange fluid is Dowtherm A. The heatexchange fluid undergoes partial boiling in the heat exchangemicrochannels 380 and 390. The ethylene and air are preheated to atemperature of 100° C. The ethylene flows through header 302 into thereaction zones 342 and 352 of the process microchannels 340 and 350,respectively. The air flows through header 304 into oxidant microchannel360. The air flows through oxidant microchannel 360 into orifices 370,and through orifices 370 into the reaction zones 342 and 352 where itmixes with the ethylene. The ethylene and air contact the catalyst andundergo reaction to form a product comprising acetic acid. The catalystcontact time is 50 ms. The product exits the reaction zones 342 and 352at a temperature of 285° C. The product is quenched to a temperature of125° C. in 50 milliseconds in recuperator 308.

Example 2

The reactant composition contains a mixture of ethylene, acetic acid,water and nitrogen at a volumetric ratio of 50:20:1:21. The source ofoxygen is oxygen. The oxygen is mixed with the reactant compositionusing staged addition, the volumetric ratio of the reactant compositionto the oxygen when fully mixed being 92:8. The catalyst is an oxidationcatalyst. The heat exchange fluid is Dowtherm A. The heat exchange fluidundergoes partial boiling in the heat exchange microchannels 380 and390. The reactant composition and oxygen are preheated to a temperatureof 100° C. The reactant composition flows through header 302 into thereaction zones 342 and 352 of the process microchannels 340 and 350,respectively. The oxygen flows through header 304 into oxidantmicrochannel 360. The oxygen flows through oxidant microchannel 360 intoorifices 370, and through orifices 370 into the reaction zones 342 and352 where it mixes with the reactant composition. The reactantcomposition and oxygen contact the catalyst and undergo reaction to forma product comprising vinyl acetate. The catalyst contact time is 50 ms.The product exits the reaction zones 342 and 352 at a temperature of160° C. The product is quenched to a temperature of 110° C. in 50milliseconds in recuperator 308.

Example 3

The hydrocarbon reactant is propylene. The source of oxygen is air. Theair is mixed with the propylene using staged addition, the volumetricratio of air to propylene when fully mixed being 94:6. The catalyst isan oxidation catalyst. The heat exchange fluid is Dowtherm A. Thepropylene and air are preheated to a temperature of 200° C. Thepropylene flows through header 302 into the reaction zones 342 and 352of the process microchannels 340 and 350, respectively. The air flowsthrough header 304 into oxidant microchannel 360. The air flows throughoxidant microchannel 360 into orifices 370, and through orifices 370into the reaction zones 342 and 352 where it mixes with the propylene.The propylene and air contact the catalyst and undergo reaction to forma product comprising acrolein. The catalyst contact time is 50 ms. Theproduct exits the reaction zones 342 and 352 at a temperature of 360° C.The product is quenched to a temperature of 210° C. in recuperator 308.The product is then quenched to a temperature of 100° C. in 50milliseconds in quenching apparatus 314.

Example 4

The reactant composition contains of acrolein and steam at a volumetricratio of 6:10. The source of oxygen is air. The air is mixed with thereactant composition using staged addition, the volumetric ratio of airto the reactant composition when fully mixed being 84:16. The catalystis an oxidation catalyst. The heat exchange fluid is Dowtherm A. Thereactant composition and air are preheated to a temperature of 100° C.The reactant composition flows through header 302 into the reactionzones 342 and 352 of the process microchannels 340 and 350,respectively. The air flows through header 304 into oxidant microchannel360. The air flows through oxidant microchannel 360 into orifices 370,and through orifices 370 into the reaction zones 342 and 352 where itmixes with the reactant composition. The reactant composition and aircontact the catalyst and undergo reaction to form a product comprisingacrylic acid. The catalyst contact time is 50 ms. The product exits thereaction zones 342 and 352 at a temperature of 275° C. The product isquenched to a temperature of 50° C. in 50 milliseconds in recuperator308.

Example 5

The reactant composition contains propane and steam at a volumetricratio of 25:65. The source of oxygen is oxygen. The oxygen is mixed withthe reactant composition using staged addition, the volumetric ratio ofoxygen to the reactant composition when fully mixed being 10:90. Thecatalyst is an oxidation catalyst. The heat exchange fluid is steam. Thereactant composition and oxygen are preheated to a temperature of 200°C. The reactant composition flows through header 302 into the reactionzones 342 and 352 of the process microchannels 340 and 350,respectively. The oxygen flows through header 304 into oxidantmicrochannel 360. The oxygen flows through oxidant microchannel 360 intoorifices 370, and through orifices 370 into the reaction zones 342 and352 where it mixes with the reactant composition. The reactantcomposition and oxygen contact the catalyst and undergo reaction to forma product comprising acrylic acid. The catalyst contact time is 50 ms.The product exits the reaction zones 342 and 352 at a temperature of400° C. The product is quenched to a temperature of 210° C. in 50milliseconds in recuperator 308. The product is quenched to atemperature of 50° C. in 50 milliseconds in quenching apparatus 314.

Example 6

The reactant composition contains propene, nitrogen and steam at avolumetric ratio of 6.7:62:20. The source of oxygen is oxygen. Theoxygen is mixed with the reactant composition using staged addition, thevolumetric ratio of oxygen to the reactant composition when fully mixedbeing 11.3:88.7. The catalyst is an oxidation catalyst. The heatexchange fluid is Dowtherm A. The reactant composition and oxygen arepreheated to a temperature of 200° C. The reactant composition flowsthrough header 302 into the reaction zones 342 and 352 of the processmicrochannels 340 and 350, respectively. The oxygen flows through header304 into oxidant microchannel 360. The oxygen flows through oxidantmicrochannel 360 into orifices 370, and through orifices 370 into thereaction zones 342 and 352 where it mixes with the reactant composition.The reactant composition and oxygen contact the catalyst and undergoreaction to form a product comprising acrylic acid. The catalyst contacttime is 50 ms. The product exits the reaction zones 342 and 352 at atemperature of 360° C. The product is quenched to a temperature of 225°C. in recuperator 308. The product is then quenched to a temperature of50° C. in 50 milliseconds in quenching apparatus 314.

Example 7

The hydrocarbon reactant is xylene. The source of oxygen is oxygen. Theoxygen is mixed with the xylene using staged addition, the volumetricratio of oxygen to the xylene when fully mixed being 99:1. The catalystis an oxidation catalyst. The heat exchange fluid is steam. The xyleneand oxygen are preheated to a temperature of 120° C. The xylene flowsthrough header 302 into the reaction zones 342 and 352 of the processmicrochannels 340 and 350, respectively. The oxygen flows through header304 into oxidant microchannel 360. The oxygen flows through oxidantmicrochannel 360 into orifices 370, and through orifices 370 into thereaction zones 342 and 352 where it mixes with the xylene. The xyleneand oxygen contact the catalyst and undergo reaction to form a productcomprising phthalic anhydride. The catalyst contact time is 50 ms. Theproduct exits the reaction zones 342 and 352 at a temperature of 450° C.The product is then quenched to a temperature of 175° C. in 50milliseconds in recuperator 308. The product is quenched to atemperature of 50° C. in 50 milliseconds in quenching apparatus 114.

Example 8

The reactant composition contains propane and ammonia at a volumetricratio of 6:7. The source of oxygen is air. The air is mixed with thereactant composition using staged addition, the volumetric ratio of airto the reactant composition when fully mixed being 87:13. The catalystis an ammoxidation catalyst. The heat exchange fluid is steam. Thereactant composition and oxygen are preheated to a temperature of 150°C. The reactant composition flows through header 302 into the reactionzones 342 and 352 of the process microchannels 340 and 350,respectively. The air flows through header 304 into oxidant microchannel360. The air flows through oxidant microchannel 360 into orifices 370,and through orifices 370 into the reaction zones 342 and 352 where itmixes with the reactant composition. The reactant composition and aircontact the catalyst and undergo a reaction to form a product comprisingacrylonitrile. The catalyst contact time is 50 ms. The product exits thereaction zones 342 and 352 at a temperature of 460° C. The product isquenched to a temperature of 160° C. in 50 milliseconds in recuperator308.

EXAMPLES 9-12

In the following Examples 9-12, the reaction process illustrated in FIG.2 is used. In these examples, the hydrocarbon reactant, and oxygen orsource of oxygen, and optionally ammonia, are premixed and preheatedprior to entering the process microchannels. Upon entering the processmicrochannels, the reactants contact a catalyst and undergo anexothermic reaction to form a desired product. The process microchannelsare subjected to cooling during this reaction using an adjacent heatexchanger. The product is then quenched. The process microchannels havea reaction zone containing the catalyst, and a channel zone downstreamof the catalyst wherein the product is subjected to cooling prior toexiting the process microchannels.

Example 9

The hydrocarbon reactant is ethane. The source of oxygen is oxygen. Theoxygen is mixed with the ethane, the volumetric ratio of oxygen toethane being 18:82. The catalyst is an oxidation catalyst. The heatexchange fluid is air. The ethane and oxygen are preheated to atemperature of 200° C. and then flow into the process microchannelswhere they contact the catalyst and undergo an exothermic reaction toform a product comprising acetic acid. The catalyst contact time is 50ms. The product exits the reaction zone within the process microchannelsat a temperature of 260° C., and exits channel zone within the processmicrochannels at a temperature of 210° C. The product is quenched to atemperature of 50° C. in 50 milliseconds in quenching apparatus 136.

Example 10

The hydrocarbon reactant is propane. The source of oxygen is air. Theair is mixed with the propane, the volumetric ratio of air to propanebeing 20:80. The catalyst is an oxidation catalyst. The heat exchangefluid is steam. The propane and air are preheated to a temperature of200° C. and then flow into the process microchannels where they contactthe catalyst and undergo an exothermic reaction to form a productcomprising acrolein. The catalyst contact time is 25 ms. The productexits the reaction zone within the process microchannels at atemperature of 480° C., and exits the channel zone within the processmicrochannels at a temperature of 220° C. The product is quenched to atemperature of 100° C. in 50 milliseconds in quenching apparatus 136.

Example 11

The reactant composition contains a mixture of n-butane and water at avolumetric ratio of 1:1. The source of oxygen is air. The air is mixedwith the reactant composition, the volumetric ratio of air to thereactant composition being 98:2. The catalyst is an oxidation catalyst.The heat exchange fluid is steam. The reactant composition and air arepreheated to a temperature of 200° C. and then flow into the processmicrochannels where they contact the catalyst and undergo an exothermicreaction to form a product comprising maleic anhydride. The catalystcontact time is 50 ms. The product exits the reaction zone within theprocess microchannels at a temperature of 460° C., and exits the channelzone within the process microchannels at a temperature of 220° C. Theproduct is quenched to a temperature of 150° C. in 50 milliseconds inquenching apparatus 136.

Example 12

The reactant composition contains a mixture of propylene and ammonia ata volumetric ratio of 8.5:10.5. The source of oxygen is air. The air ismixed with the reactant composition, the volumetric ratio of air to thereactant composition being 81:19. The catalyst is an ammoxidationcatalyst. The heat exchange fluid is steam. The reactant composition andair are preheated to a temperature of 200° C. and then flow into theprocess microchannels where they contact the catalyst and undergo anexothermic reaction to form a product comprising acrylonitrile. Thecatalyst contact time is 50 ms. The product exits the reaction zonewithin the process microchannels at a temperature of 440° C., and exitsthe channel zone within the process microchannels at a temperature of220° C. The product is quenched to a temperature of 150° C. in 50milliseconds in quenching apparatus 136.

While the invention has been explained in relation to various detailedembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

1. An apparatus, comprising: a microchannel reactor, the microchannelreactor comprising a plurality of process microchannels; and a quenchingapparatus.
 2. The apparatus of claim 1 wherein the process microchannelsare parallel to each other, the microchannel reactor further comprising:a header providing a passageway for fluid to flow into the processmicrochannels; and a footer providing a passageway for fluid to flowfrom the process microchannels.
 3. The apparatus of claim 2 furthercomprising a microchannel mixer for feeding reactants into the header.4. The apparatus of claim 1 wherein mixers are disposed within theprocess microchannels.
 5. The apparatus of claim 1 wherein the processmicrochannels have entrances at different points along the length of theprocess microchannels to permit entry of one or more reactants into theprocess microchannels.
 6. The apparatus of claim 1 wherein the processmicrochannels contain a bulk flow path.
 7. The apparatus of claim 1wherein the process microchannels are made of a material comprisingsteel; monel; inconel; aluminum; titanium; nickel; platinum; rhodium;copper; chromium; brass; alloys of any of the foregoing metals;polymers; ceramics; glass; composites comprising one or more polymersand fiberglass; silicon; or a combination of two or more thereof.
 8. Theapparatus of claim 1 wherein each process microchannel has an internaldimension of height or width of up to about 10 mm.
 9. The apparatus ofclaim 1 further comprising a heat exchanger in thermal contact with theprocess microchannels.
 10. The apparatus of claim 9 wherein the heatexchanger comprises a plurality of heat exchange channels.
 11. Theapparatus of claim 10 wherein the heat exchange channels aremicrochannels.
 12. The apparatus of claim 10 wherein the heat exchangechannels are aligned to provide a flow of heat exchange fluid in theheat exchange channels that is in a direction that is cross-currentrelative to the flow of fluid in the process microchannels.
 13. Theapparatus of claim 10 wherein the heat exchange channels are aligned toprovide a flow of heat exchange fluid in the heat exchange channels thatis in a direction that is co-current or counter-current relative to theflow of fluid in the process microchannels.
 14. The apparatus of claim10 wherein each heat exchange channel has an internal dimension ofheight or width of up to about 10 mm.
 15. The apparatus of claim 10wherein the heat exchange channels are made of a material comprisingsteel; monel; inconel; aluminum; titanium; nickel; platinum; rhodium;copper; chromium; brass; alloys of any of the foregoing metals;polymers; ceramics; glass; composites comprising one or more polymersand fiberglass; silicon; or a combination of two or more thereof. 16.The apparatus of claim 1 wherein the quenching apparatus is integralwith the microchannel reactor.
 17. The apparatus of claim 1 wherein thequenching apparatus comprises a microchannel heat exchanger.
 18. Theapparatus of claim 1 wherein product exits the microchannel reactor in aproduct line and the quenching apparatus comprises a heat exchangeradjacent to the product line.
 19. The apparatus of claim 1 wherein thequenching apparatus comprises a mixer capable mixing product with acooling fluid.
 20. The apparatus of claim 1 wherein a reaction isconducted in the microchannel reactor and the quenching apparatuscomprises a passageway with a dimension equal to or less than the quenchdiameter for the reaction.
 21. The apparatus of claim 1 wherein thequenching apparatus comprises at least one microchannel.
 22. Theapparatus of claim 1 further comprising a premixing and preheatingapparatus.
 23. The apparatus of claim 22 wherein the premixing andpreheating apparatus comprises a microchannel mixer.
 24. The apparatusof claim 22 wherein the premixing and preheating apparatus is integralwith the microchannel reactor.
 25. The apparatus of claim 1 wherein themicrochannel reactor comprises a microchannel reactor core.
 26. Theapparatus of claim 25 wherein the microchannel reactor core comprises areactor zone, and a manifold and recuperator zone.
 27. The apparatus ofclaim 1 further comprising a plurality of staged addition microchannels,each staged addition microchannel being adjacent to at least one processmicrochannel, each staged addition microchannel having a common wallwith the at least one process microchannel, and a plurality orifices inthe common wall.
 28. The apparatus of claim 1 wherein a catalyst is inthe process microchannels.
 29. The apparatus of claim 28 wherein thecatalyst comprises a flow-by structure or a flow-through structure. 30.The apparatus of claim 28 wherein the process microchannels haveinterior surfaces and the catalyst is coated on the interior surfaces.31. The apparatus of claim 28 wherein the catalyst is in the form ofparticulate solids, foam, felt, wad, honeycomb, fin, or a combination oftwo or more thereof.
 32. The apparatus of claim 28 wherein the catalysthas a serpentine configuration.
 33. The apparatus of claim 28 whereinthe catalyst is in the form of a flow-by structure with an adjacent gap,a foam with an adjacent gap, a fin structure with gaps, a washcoat on aninserted substrate, or a gauze that is parallel to the flow directionwith a corresponding gap for flow.
 34. The apparatus of claim 28 whereinthe catalyst comprises a porous support, an interfacial layer, and acatalytic material.
 35. The apparatus of claim 28 wherein the catalystcomprises a porous support, a buffer layer, an interfacial layer, and acatalytic material.
 36. The apparatus of claim 28 wherein the catalystcomprises at least one metal, metal oxide or mixed metal oxide of Mo, W,V, Nb, Sb, Sn, Pt, Pd, Cs, Zr, Cr, Mg, Mn, Ni, Co, Ce, or a mixture oftwo or more thereof.
 37. The apparatus of claim 36 wherein the catalystfurther comprises a metal, oxide or mixed metal oxide of an alkali oralkaline earth metal, a transition metal, a rare earth metal, alanthanide, or a mixture of two or more thereof.
 38. The apparatus ofclaim 36 wherein the catalyst further comprises P, Bi or a mixturethereof.
 39. The apparatus of claim 28 wherein the catalyst comprises asupport comprising a metal oxide, silica, mesoporous material,refractory material, or a combination of two or more thereof.
 40. Theapparatus of claim 27 wherein the microchannel reactor comprises areactant header providing a passageway for reactant to flow into theprocess microchannels, and an oxidant header providing a passageway foroxygen or a source of oxygen to flow into the staged additionmicrochannels.
 41. The apparatus of claim 10 further comprising a heatexchange header providing a passageway for heat exchange fluid to flowinto the heat exchange channels and a heat exchange footer providing apassageway for heat exchange fluid to flow from the heat exchangechannels.
 42. An apparatus, comprising: a plurality of processmicrochannels, the process microchannels being aligned in parallel andcontaining catalyst; a plurality of staged addition microchannels, eachstaged addition microchannel being adjacent to at least one processmicrochannel, each staged addition microchannel having a common wallwith the at least one process microchannel; a plurality of orifices ineach common wall; a plurality of heat exchange channels for exchangingheat with the process microchannels; a reactant header providing apassageway for reactant to flow into the process microchannels; anoxidant header providing a passageway for oxygen or a source of oxygento flow into the staged addition microchannels; a product footerproviding a passageway for product to flow from the processmicrochannels; a heat exchange header providing a passageway for heatexchange fluid to flow into the heat exchange channels; a heat exchangefooter providing a passageway for heat exchange fluid to flow from theheat exchange channels; and a quenching apparatus.
 43. A process formaking an epoxide, comprising: reacting a reactant compositioncomprising an unsaturated aliphatic hydrocarbon reactant and oxygen or asource of oxygen in the presence of an oxidation catalyst in one or moreprocess microchannels of a microchannel reactor to form the epoxide; andquenching the epoxide.
 44. The process of claim 43 wherein the catalystcomprises at least one metal, metal oxide or mixed metal oxide of Mo, W,V, Nb, Sb, Sn, Pt, Pd, Cs, Zr, Cr, Mg, Mn, Ni, Co, Ce, or a mixture oftwo or more thereof; and a metal, oxide or mixed metal oxide of analkali or alkaline earth metal, a transition metal, a rare earth metal,a lanthanide, or a mixture of two or more thereof.
 45. The process ofclaim 44 wherein the catalyst further comprises a support comprising ametal oxide, silica, mesoporous material, refractory material, or acombination of two or more thereof.
 46. The process of claim 43 whereineach process microchannel has an entrance, an exit and an elongatedsection extending between the entrance and the exit, each processmicrochannel further comprising at least one additional entrance in theelongated section, the unsaturated aliphatic hydrocarbon reactantflowing through the entrance in each process microchannel, the oxygen orsource of oxygen entering each process microchannel through the at leastone additional entrance in the elongated section and contacting theunsaturated aliphatic hydrocarbon reactant in the process microchannel.47. The process of claim 43 wherein the feed composition includes adiluent material.
 48. The process of claim 47 wherein the volume ratioof diluent material to hydrocarbon reactant in the reactant compositionis from zero to about 80% by volume.
 49. The process of claim 48 whereinthe diluent material comprises nitrogen, helium, carbon dioxide, liquidwater, steam, or a mixture of two or more thereof.
 50. The process ofclaim 43 wherein the hydrocarbon reactant comprises ethylene and theepoxide comprises ethylene oxide.
 51. The process of claim 43 whereinduring the quenching the epoxide is cooled to a temperature in the rangefrom about 50° C. to about 300° C.
 52. The process of claim 43 whereinduring the quenching the epoxide is cooled to a temperature in the rangefrom about 50° C. to about 200° C.
 53. The process of claim 43 whereinduring the quenching the epoxide is cooled to a temperature in the rangefrom about 50° C. to about 150° C.
 54. The process of claim 43 whereinduring the quenching the epoxide is cooled to a temperature in the rangefrom about 50° C. to about 300° C. over a period of time in the rangefrom about 5 to about 100 milliseconds.